I reach Villa Ángela frustrated, tired and sweaty. But it’s Saturday. As soon as Monday comes I’ll have another go at tracking down Yogui Quevedo. Tonight is the last night of carnival. I’m not a big fan of the comparsas, but if you’re in Villa Ángela, General San Martín or Quitilipi, attending carnival is more or less compulsory.

It must be some forty degrees centigrade in the moonlight shining down on the corsodrome, a kind of open-air stadium erected along the street outside the old railway station, which is now a cultural centre. The stands have been built on one side of the street. That’s where the masses watch from. On the other side there are tables and chairs, where you can enjoy the show a little more comfortably. Since it’s the last night of carnival, entrance is free. But the chairs and tables are quite expensive and need to be booked well in advance. I belong to the privileged set who occupy this side of the corsodrome. This year, or this final evening, I’m not sure, there’s no table service, unlike other times I’ve come. Some wooden boards on oil drums, set up in the streets around, become makeshift stalls selling chorizo rolls and beer, which comes in those plastic litre cups big enough to fit the whole bottle. They’re not very practical because it takes such balance not to spill half your drink before you reach your table, plus the beer soon gets warm. But it’s a sensible measure: carnival night, passions ablaze, a glass in the hand can always end in tragedy.

Some cities in Chaco, and in Corrientes and Entre Ríos, have a long carnival tradition in the style of Rio de Janeiro: huge comparsas of scantily-clad dancers, their winged costumes made of feathers – peacock feathers for the most expensive, and dyed ostrich feathers for the rest. Someone at my table says the feathers come from Africa. Their first stop is Brazil, where they’re washed and dyed beautiful colours. People once tried making artificial feathers to cut costs, but they were no good. The fake feathers weren’t as elegant or supple as the real ones. As well as the feathers, millions of sequins and beads are hand-sewn onto the costumes and boots. A friend of mine makes boots for all the dancers: they’re made of tough material, with zips and high heels. Once they leave his little factory, groups of female volunteers (some were dancers in their youth, and others never wanted to be) begin the meticulous embroidery: in the first sweltering siestas of October, sitting in the shade of the trees, drinking tereré, they make the first stitches, and then on they go, dazzled by the sun’s glare on the sequins, until the end of January.

In Villa Ángela there are two legendary comparsas, a third that’s slightly newer, and always a fourth that flourishes and dies in that one carnival. The two stalwarts that share the most fans are Ara Sunú – the lower-class one from the wrong side of the tracks, which has the prettiest girls and the finest male bodies, forged by construction and demolition work; and Hawaianas – the fancier one, with the best-groomed girls and gym-toned boys, but also the best samba school. Ara Sunú means stormy weather, or thunder, in Guarani. There’s no prize for guessing the meaning of Hawaianas but the name does have one notable feature, which is that the locals pronounce it aguaiana, overly respecting the silent H at the beginning and skipping the final S. As with football, the people of Villa Ángela are supporters, or fans, of one or the other.

This evening I’m at a table of Hawaianas devotees, though secretly my heart belongs to Ara Sunú.

The third group in the parade was once controversial, because it arose from a fight between the couple who ran Ara Sunú: they split up, and when they shared out their possessions he took a few loyal followers and founded this group, Bahía, which is now a respectable size. And this year’s flash in the pan is Samberos de Itá Verá, who will come last in the parade, paying their dues as the newbies.

Unlike in the Rio comparsas, there isn’t a single transvestite. In this city of people descended from the first immigrants to populate the country, and others who followed later from Eastern Europe, people are conservative. Neither transvestites nor homosexuals of any kind are welcome around here. Still, it’s inevitable that some gay people slip into the hallowed ranks of carnival and live those four wild nights to the fullest, stamping their heels on the corsodrome’s concrete floor, crotches thrust out, shiny microscopic G-strings shaking to the rhythm of the drums.

The first comparsa, Ara Sunú, goes by, and when they announce the second I decide it’s a good time to go to the bathroom: in the intervals it’s impossible.

Even now, there’s a queue outside the first two portable toilets I come to. They aren’t divided into women’s and men’s, but the queues form according to the gender of the people waiting. In front of me, two girls of ten or eleven, and another of five. Outside the next cubicle, six guys. This part of the street is dark and the toilets are right by a building site. The girls, on the cusp of adolescence, dressed in hot pants and vests that press tight against their budding nipples, practise dance moves on the spot, twirling their wrists like the older girls who strut their stuff in the corsodrome. They critique their attempts at a particular step, one explains to the other how to do it properly. Some of the guys queuing for the toilet watch. I don’t like them looking at the girls, although in the gloom I can’t tell how they’re looking at them. When the youngest comes out, rearranging her pink shorts, another of the girls says I can go next. Although I’m about to wet myself, I smile and say no, they can go, I’ll keep an eye on the door. And I raise my voice for the last part, so our neighbours at the other toilet can hear me. Just in case.

The rest of the night will follow the same pattern: the comparsa goes by with some two hundred and something members, a spray-foam fight in the interval, trips to the bathroom and refreshment stands, and so on until the early hours.

When we’re finally heading towards the cars parked in a field nearby, I hear a still-childish voice shouting: As if I’d let you fuck me, are you crazy, you fucking fag, you piece of shit. A girl of around twelve who looks like one of my friends from the toilet queue, dark-skinned, thin, followed by a gaggle of kids of a similar age, is having a slanging match with a cluster of guys. Although her opponents have now fallen silent and are backing away, embarrassed by the girl’s filthy mouth, she follows them in order to keep yelling.

A feisty little carnival kid. A girl alone on a carnival night.

After Sunday lunch one day, Coco Valdez, my father-in-law, tells me about the time he saw a dead girl. They were having dinner one night with his wife’s parents, who had a little café opposite the train station. Someone knocked at the door and he went to see who it was. A boy he knew, whose surname was Lencina, asked if he could use their phone to call the police. Yes, of course, come inside, but what was going on? On some waste ground, not far away, Lencina had come across the body of a woman. He couldn’t be sure because it was night-time, although the moon was bright, but he thought she was dead and he didn’t want to touch her.

They waited in the café, which was closed at that hour, for the police to arrive. The officer came on a bicycle because the patrol car was at the garage being repaired.

Have you got a vehicle? he asked Coco. Come on, come with us.

Lencina led them through the wasteland. In the weeds, by the side of a path that had formed by being used as a shortcut, they found the girl. When the police officer shone a torch on her face, the three of them looked at one another, stunned. She was a Carahuni, the daughter of a traditional family in the town, and related to Coco Carahuni, a well-known car dealer. Someone had stabbed her in the stomach.

My father-in-law drove away in his truck with the girl’s corpse, the police officer and Lencina, who had quickly turned from a witness to a suspect, though they released him the next day. The boy had nothing to do with it, he’d just had the bad luck to be crossing the wasteland.

The Carahuni crime remains a mystery, forty years on. At the time, a man from Rosario who’d recently moved to Villa Ángela was arrested for the girl’s murder, but they never found a motive. Apparently the man had threatened his wife: If you don’t stop messing me around, I’ll deal with you like I dealt with that Carahuni girl. And she reported him to the police.

Someone else around the table recalls a more recent case, from 1997, involving Andrea Strumberger, a girl of sixteen and a secondary school student. She was an Evangelical Christian and that Sunday she set off on her moped for the Asamblea de Dios Evangelical church. She never arrived, and the next day her body showed up in some wasteland. She’d been raped and beaten to death. Her brother-in-law was arrested for the murder. Everyone knew him, because he was the relative who’d called the most vocally for the case to be resolved.

On Monday I go back to Sáenz Peña. Uninvited, without calling ahead, without agreeing a time or place. I get there in the morning. I’m going to find Yogui Quevedo whatever it takes, and we’re going to talk.

Not that it will be easy. The helpful man I spoke to on the phone a few months ago has suddenly turned evasive.

I call his mobile as soon as I arrive. No luck despite several attempts, always the voicemail.

It’s mid-morning and I’m in the city centre. Last time I was here I saw it from a bus, then a taxi, then I walked a few blocks. Today I have more time, and since Yogui isn’t picking up, I set off down the pedestrianised street in search of a bar. The heat is stifling and a cold drink somewhere with air con would be good. Wait in the shade.

The pedestrianised Calle San Martín must be about ten blocks long, and I walk all the way down it looking in shop windows. There are no bars. On my whole expedition I find just one. I look in from outside and see several tables with people at them, all men of fifty or more, drinking whisky or beer, smoking and talking in loud voices. Surely I passed more than one bar, I think, and I walk up and down the street again. But no, it seems the bar full of shouting men is the only one. I ask in a kiosk: where can I find a bar that’ll do me a soft drink, somewhere quiet. They point to an ice-cream parlour. I don’t want an ice cream, I want a cold drink. Yep, you can get that there too. I head towards it with misgivings, thinking they’ve seen I’m not from around there and are playing a joke on me. But no, the bar I was looking for is an ice-cream parlour. Later I learn that in Sáenz Peña there are almost no bars. The teenagers and young people don’t normally go to bars to drink. Instead they park their cars, motorbikes and pickups outside the kiosks and drink on the pavement until it’s time to go to the nightclub.

I order a Sprite in the ice-cream parlour and they bring me a litre bottle, they don’t sell anything smaller. It’s almost like a premonition, because I’m in for a long wait. After more failed attempts, someone finally answers Yogui’s phone. It’s not him; another man says that yes, this is Quevedo’s number, but he can’t talk because he’s in a meeting and I should call back at midday.

I take a book someone lent me out of my rucksack. It’s called Twenty-five Murders from the Sáenz Peña Crime Pages, by the local historian Raúl López. One story catches my eye, the one about the Polish girl and the Paraguayan guy, which took place in the fifties.

Rosa was the daughter of a Polish couple. She was a sportswoman and worked in a shop, La Ideal, one of those big stores that sell everything: clothes, shoes, wedding dresses, cuts of fabric, bed linen and towels, catering for all the family. As captain of the women’s volleyball team, she’d won a handful of medals and trophies in provincial and national games. The photo accompanying the article shows her on a trip with her teammates: she was a beautiful girl, robust and healthy. In the same club where she achieved this sporting success, she met the person who would be first her lover and then her murderer: Juan, a young Paraguayan who’d got a job in the sports club bar. The attraction was immediate: she a little cautious, shy; he overpowering, persistent, sticky like the scent of the orange blossom that scatters the streets of his country. They began dating. Her parents didn’t approve of the relationship, but she was ready for anything, she’d never been so in love, never had anyone whisper such tender words in her ear, never felt so womanly or so desired as she did on that cheap hotel bed where she made love with Juan whenever she could sneak out of the house.

However, her boyfriend soon showed himself for what he was: a possessive, jealous and violent man. Rosa, even head over heels in love, was a woman of character. The ladies’ volleyball captain got the better of the dreamy girlfriend and she broke off the relationship. Needless to say, Juan didn’t take it calmly. After the entreaties and passionate declarations came threats. And a letter printed in the town paper describing every last detail of his relations with the girl. An equivalent to the videos posted online by malicious ex-lovers more than fifty years later: the public exposure of a woman’s privacy. Rosa must have thought he couldn’t go any further, that nothing could be worse for a decent, hard-working girl like her than to be stripped naked and shamed by that letter. She must have thought that if she’d survived public humiliation at the hand of her ex-boyfriend, he had no weapons left that could crush her. She got used to looking over her shoulder: no matter where she went, sooner or later she’d see him. Rejected, he’d turned to drink and lost his job. So not only did he follow her around, but when they crossed paths he yelled abuse at her, the wine slurring his words, which were always offensive.

As a precaution, she tried not to go out alone. Her mother went with her to work every day, and met her outside when she finished. One morning, the two of them were walking along arm in arm. They saw him on a street corner, but that wasn’t unusual and they carried on past, brisk, indifferent, heads high. So set on ignoring him that the hand must have come as a surprise, clasping her shoulder from behind and pulling her around, and Juan’s bloodshot eyes that seemed to beg her one last time, then the same hand drawing her towards him and the other sliding a knife into her flesh, and then her tumbling, both of them tumbling to the pavement as he stabbed her again and again, and her mother screaming, running for help. Rosa staring at him, still not understanding. Taking a long time to die. Him on top of her, thrusting the knife in and out. Her beneath him, just like in the cheap hotel bed. Him splattered all over with blood. Then, unable to bear Rosa’s blue-eyed gaze, Juan slit her throat from side to side, before plunging the same knife into his own stomach. The two bodies in a heap, spilling blood onto the pavement, just outside the shop.

Earlier, walking around, I passed the House of Culture, a large old building that had been renovated. A plaque said it used to be the Ideal store. I leave the ice-cream parlour and wander towards it. Somewhere on that block, Rosa was killed.

It’s noon on the dot and I call Yogui again. Finally he’s the one who picks up. I tell him I’m in the city, that I’ve come to interview him. That I came on Saturday as we agreed but couldn’t get hold of him, that he never answered my messages or calls. He says he was at a function with the governor all afternoon. That we can meet in half an hour at his brothers’ travel agency.

I’m a few blocks away, no more than five minutes, so I cross into the main square and sit on a bench to wait for the time to pass.

When half an hour’s almost up and I’m making my way over, I see two men chatting on the pavement. One must be Yogui, I think, without deciding which. Based on their ages it could be either. I say hello and introduce myself, and then one of them, short and dark-skinned, with large, almond-shaped eyes like a deer’s, holds out his hand. I thought you’d be older, he says, with a winning smile. He explains to the other man, who also shakes my hand, that I’m from Buenos Aires and I’m going to write a book about his sister. The man nods and says goodbye. Yogui invites me to sit on the same low wall where I sat last time. I feel the warm concrete through the fabric of my jeans. He tells me he’s waiting for the minibus from Bolivia, that his brothers are on their way back from a trip. I tell him I know, I spoke to one of them on the phone, that when I couldn’t get hold of him as arranged I called the mobile number on the board outside. He looks at me solemnly and asks if I told his brother what it was about. I say yes. He shakes his head. No, no, he says, they don’t want anything to do with this, I’m the only one who keeps going with it all. He says we should meet later instead, they won’t like seeing me with him when they arrive, and besides, he has to work. He works with them, he emphasises, as if my being there put his source of employment at risk.

Here at five, ok? I’m by myself in the evenings.

He’s just finished speaking when the white minibus pulls in, packed with people and equipment. The driver gets out, waves at his brother and glances at me, then carries on walking towards the office. Yogui doesn’t introduce us.

See you later, he says, I can’t talk now. And he shakes my hand again.

I check the time on my phone. It’s almost five hours until five o’clock. I walk all the way down the pedestrianised street again, this time looking for a restaurant. There aren’t many options. I go for one at the end nearest the square, because I know that’s where I’ll have to spend all the remaining hours until five.

I order a sandwich and a mineral water. I watch the news on TV, and every time I reach for my glass I have to peel my arm off the rubber seat. There aren’t many customers. My gaze shifts from the TV to the window, which will be busier than the screen until a quarter past one. From then on, deserted, motionless. The city has stopped and it won’t start again until five.

I sit on a bench in the shade and take off my trainers. I rub the soles of my feet on the rough, close-cropped grass. It’s very hot. Not the slightest breeze. The only souls out and about at this hour are a man in his fifties with very dark hair and a bag in his hand, a tradesman dozing on the ground with his head resting on his rucksack, two kissing teenagers half-hidden by a tree, and me. No people, no cars, no dogs. All shut up safe and sound in their houses, waiting for the fierce heat to subside. If I listen closely, I think I can catch the soft humming of the split air con units, the motorised clanking of the older systems, the patter of ceiling fans. I’m jealous. I should have found a hotel, if only for the siesta.

Before me stands the cathedral, magnanimous. The further a place from the hand of God, the more imposing the building that honours him. On the day María Luisa went missing, the cathedral and the square would have been teeming with the faithful, worshipping the Immaculate Conception. Maybe she even passed this way, unnoticed in the crowd, to leave a flower for the Virgin. From my place in the square, I can see that it’s closed. Pity. I would have liked to go in: it’s always cooler inside churches.

I decide not to look at the time again. Whenever I take out my phone and check, only a few minutes have gone by. I set the alarm for five to five.

Suddenly I see them appear in a corner of the square. I don’t know if they’re real or part of a dream. From a distance the figures look hazy, their outlines rippling like a mirage. When they get closer, I see that they’re real. Two Mennonite men in denim dungarees, check shirts with the sleeves rolled up to the elbows, black lace-up shoes, white hats, and bags in their hands. Behind them, emerging into view as they draw nearer, two women in flowery dresses and aprons, with blue scarves covering their hair. One has a baby in her arms. Not far from the city there’s a Mennonite community. Their bags must be full of the cheeses and homemade produce they make and bring here to sell.

They cross the road, seeking the shade on the pavement. I watch as they drift slowly along, more prisoners of the siesta. They stop at the huge window of a home appliances store and gaze in as if sharing something illicit, a minor sin: feasting their eyes for a time on those forbidden inventions.

I follow the tradesman’s lead and stretch out on the bench, my rucksack under my head. I must have fallen asleep at some point because I wake up in the middle of a dream in which thousands of cicadas are singing in unison. It’s my phone alarm vibrating inside my rucksack. Five to five.

I sit up and pull on my trainers. Gradually things begin to stir. The street fills up with mopeds. The odd car, the odd bicycle, people on foot. The shops open at five.

I stop in a service station and ask for the key to the toilet. I wash my face, neaten up my hair, put some chewing gum in my mouth. I can feel my heart beating faster. Finally I’m going to talk to María Luisa’s brother.

But not at five, as we’d agreed. Yogui Quevedo keeps me waiting another half-hour, sitting yet again on that blessed wall.

As I wait, I have the feeling I’m being watched. I look up at the big broken windows of the building, which has another two floors above the Quevedos’ office. I think I see a curtain move. I feel slightly uneasy. I type out a message and press send. Yogui replies that he’s on his way. All in capitals, as if he’s shouting, as if we were still too far apart for me to hear him. And we must be, since it’s another fifteen minutes before he shows up.

Finally I see him come round the corner and cross the street, smiling at me. He holds out his hand. He’s just showered, his shiny black hair is flat against his skull, and he smells of an aftershave that reminds me of one my father used to use. He doesn’t apologise for being late.

He takes out a key and opens the door. We step into a dim, down-at-heel little office. He puts the envelope he’s been holding on the rickety Formica table that serves as a desk and tells me to make myself at home. I sit on one of the three chairs, which are also made of Formica. He puts a fan near the open door. I look over. There’s a large carob-wood shelving unit opposite chock full of spirits and whisky bottles, lined up and covered in dirt. They must buy them on those trips they make to the border, meaning to sell them on, and then they accumulate there, forgotten. As well as that table there’s another, smaller one, at the back, with a portable stove on top connected to a gas cylinder. He lights it and starts heating some water. While he prepares the mate, we talk about the weather. They said on the radio that it’s going to rain this evening, but the sky is blue and cloudless.

He comes over to the table with the mate ready and sits down. He slides the envelope towards me.

I brought you something.

I look at him, I look at the envelope, but I don’t move.

It’s a photo of my sister.

I’ve still never seen a photo of María Luisa. Just a pencil sketch in the paper. I’m interested to know what she really looked like. The drawing I saw was very rough, like one of those identikits the police put together. But my hands don’t do as I tell them and I go on staring at the envelope without opening it, without even touching it.

It’s a photo of her in the morgue, he says eventually.

My stomach turns over.

I don’t know if you’ll want to see it. I bought it off a police photographer.

I can’t understand why anyone would want to have a photo like that. Before I have the chance to ask, he tells me: Since here they did fuck all, I got in touch with a magazine in Buenos Aires, one of the true crime ones. Esto, I think it was. Anyway, you know how those magazines like morbid shit. And I wanted the rest of the country to know about my sister’s murder, in case that gave people here a kick up the arse.

I’m not convinced by his explanation, but I reach for the envelope and quickly pull out the photo. It’s an enlargement. I glance at it briefly. The poor thing. I check inside the envelope, hoping he’s also brought one of María Luisa alive. But there’s nothing else. I look up and he’s watching me.

See how she ended up. Completely disfigured. I only recognised her because of a scar on her leg, from when I chucked a tape player at her one time.

You threw a tape player at her?

Yeah, we were arguing. You know what brothers and sisters are like. I didn’t mean to actually hurt her...

I’d like to see a photo of her.

I don’t have any. There was one in the paper, of her with my mum and my sister-in-law, but it got lost.

The fan by the door just drags the hot air in from outside and moves it in circles above us. I’m sweating, and I feel a bit annoyed and also a bit tired. Or sad.

I tell him the mate’s got cold. Maybe if we go back to the moment when we’d just arrived, if he puts the kettle on the stove again and adds fresh leaves and comes back and sits down and I forget about the envelope with the photo, we can start the interview.

He waits for the kettle to start whistling and sprinkles more mate leaves into the gourd. He drinks the first one, then refills it and passes it to me.

Better?

I nod, and tell him I’m surprised he doesn’t drink tereré like everyone else there.

We’ve got no fridge.

Has he been working with his brothers for long?

On and off, helping them out. I took voluntary retirement. For a long time I worked driving a rubbish truck.

I ask if he remembers the last time he saw his sister and he tells me it was the same day she disappeared, around 10 a.m. He was on a bus, on his way to the job he had then in a radio repair shop, and since it was a holiday or half-holiday he was going in later than usual. He saw her through the window: she was on the pavement outside the house where she worked as a maid, she had a shopping bag in her hand and was talking to a boy on a bicycle, leaning on the handlebars as they chatted. The boy was Francisco Suárez, an employee of Don Gómez, who Yogui knew by sight. Were it not for what happened afterwards, he’d probably have forgotten the scene: his teenage sister flirting with a boy on the pavement. If things had carried on as normal, perhaps he’d only have remembered in order to tease her, the way older brothers do when their sisters are discovering boys.

Did she have a boyfriend? Was this Suárez guy her boyfriend?

No, no. Well, not that I know of...

Yogui was twelve years older than María Luisa, so yes, he probably wouldn’t have known.

He tells me María Luisa didn’t go to school and her only friends were from the neighbourhood. She was a real homebody, and this was her first job.

However, in that short, intense week that marked her leaving the house to join the adult world, the world of going out to work, María Luisa made two friends: Norma Romero and Elena Taborda, two girls slightly older than her, and more streetwise. Quevedo blames them for leading her astray. As if her death were a punishment for something she’d been doing wrong. According to him, that day, probably the last of María Luisa’s short life, she met up with her new friends after work and they invited her to spend the afternoon in Villa Bermejito, a village around sixty miles away on the banks of a tributary of the Bermejo river, where people had weekend homes. They were going with Francisco Suárez, Catalino Lencina and Jesús Gómez, the boss of the first two.

That’s what the girls said the first time they were questioned, and their statement was backed up by a petrol station attendant who confirmed that he’d filled up a car containing Don Gómez, two guys and three girls. But Norma and Elena, when called before the judge, denied everything they’d told the police and filed a complaint of unlawful coercion, showing the marks from beatings they’d received to make them give false testimony.

The judge for the case, Oscar Sudría, believes the two girls hold the key. He’s convinced that they (and the murderer or murderers) are the only people left who can say exactly what happened on that December 8th.

Over the twenty years it took him to close the case, he summoned them several times to make statements. It wasn’t easy because the girls left Sáenz Peña soon after the murder and never stayed long in the same place. So every two or three years, first he had to find out where they were, and then he had to bring them back. He saw them at weekends, never with the police, because, after their complaints of illegal coercion during the 1983 investigation, if there was anyone they didn’t trust it was the police. As the years went by, he watched them grow into women, have children. But he could never get a word out of either of them.

The petrol station attendant, when called in to make another statement, changed his story as well: he’d never seen Don Gómez and María Luisa together.

Quevedo maintains that they’re lying, that these key witnesses in his sister’s rape and murder were bought off by Gómez and his immense fortune – Gómez, who even Quevedo still calls Don Gómez, as if he inspired in him a strange sort of fear or respect.

We’re interrupted by his phone. He answers and begins a conversation, practically shouting. The signal’s bad, it’s a call from Buenos Aires.

On the other end is an adviser to the Chaco politician Antonio Morante. They chat for a bit. Quevedo tells him about me, hands me the phone, the adviser and I say hello, he tells me something about a bill they’re putting forward in the Chamber, we swap email addresses. I return the handset, Yogui says a few more words then hangs up. He seems pleased. Since the line wasn’t great, I didn’t fully understand about the bill they’re planning to present in the Honourable Chamber of Deputies of the Nation.

Is it to request the case be reopened? I ask Yogui.

No, it’s for them to condemn the lack of justice in my little sister’s case.

Oh, I say, disappointed.

Suddenly it starts to rain. The radio was right after all.