So where did the roots of Boston’s immoral sick personality lie? Is it nature or nurture that makes a psychopath? Were there any signposts in his early development and upbringing to suggest that he would become such a demonic human being?

Meeting him in Laguna, Russell Boston was generous in sharing with me his vivid recollections of his depraved father’s reckless and lawless life and his family’s history. He spoke openly and with complete frankness.

Silas Duane Boston was born on 20 March 1941 in Shasta County Hospital, Clear Creek, Rural Shasta, in Northern California to working-class parents, Russell and Mary Evelyn Sellers Boston, who divorced shortly after he was born. He attended Elk Grove High School in Sacramento County. Hillbilly, redneck, white trailer trash, he fitted a variety of epithets – Boston was all of those and much, much more.

The seeds for his vile character were sown from an early age. Russell explained: ‘Dad came from a broken home and claimed he was abused and beaten. He felt his mother was a tramp who betrayed him and she was the source of his serious psychological issues of abandonment and betrayal regarding women. He started stealing when he was a child because, he said, his mom left him alone for days at a time to be with her latest boyfriend and he had to feed himself.

‘Dad claimed he made his first kill when he was just eight years old. He enjoyed throwing rocks at passing railcars and he was proud that on one occasion he made a direct hit with a hobo passenger, who slumped to the floor. After that he got a thrill and a lust for killing.’

No academic, Boston was nonetheless cunning, savvy and streetwise and as tough as snakeskin. He had a fierce sense of pride and would rather see everything go to hell than suffer humiliation. His volatile temper could go from zero to murder in a heartbeat. He was a tyrant and a master of manipulation, ruling his immediate and extended family with a rod of iron. Physically and mentally abusive, those with whom he came into contact were said to live in constant fear of him, and he repeatedly threatened them with death if ever they thought about exposing the crimes he so often bragged about. The majority colluded in silence for fear of retribution either by him or his network of ‘outlaw’ contacts with whom he did ‘business’, such as burglaries, hijacking, smuggling and drug deals.

Marital breakdown, adultery, domestic violence, alcoholism, murder, sexual deviance and burglary characterised Boston’s life. Like a serpent, he could disguise his evil core well. Outwardly, he could turn on the charm and charisma at the flick of a switch; inwardly, he was cold, ruthless, with no hint of a moral compass.

Russell told me: ‘When he wasn’t showing his dark side he was well liked by those around him. He was a superb conversationalist and very successful womaniser, a gift he used with devastating effect. All my life I’ve been stupefied by Dad’s ability to attract women. My grandmother called it the “Boston Charm”, which she said Dad inherited from his father. He was able to schmooze and charm women of any walk of life and always had a plethora of girlfriends and wives. A misogynist, he had a cocky confidence, which he combined with a physiological trick of insulting women, who then craved his attention and validation. I can’t tell you how many times I saw him blatantly degrade women, only for them to come crawling back to eat out of his hand afterwards.’

Believed to have been married a staggering seven times, and siring more children than anyone can count or remember, Russell, perhaps not jokingly, says there is a village in Mexico where all of its inhabitants look like Boston! Boston always protested that he wasn’t a rapist, saying ‘I can get any chick I want.’ He had a conveyor belt of women who fell prey to his ‘charm’ and despite his timeworn, haggard appearance and violent, abusive character Boston had several girlfriends right up to the point he died. He was also an outspoken racist, yet he had Afro-American girlfriends aplenty. One of his favourite sayings was: ‘The only thing worse than a nigger is a nigger lover, and the only thing worse than a nigger lover is a snitch.’

Whilst Boston might well have been hardwired wrong, as Russell suspects, nurture undoubtedly had a large part to play in the twisted monster he turned out to be. One doesn’t have to look further than his parents for the root of his total lack of moral agency.

The matriarch of the family, Boston’s mother, fostered a culture in which her son could do no wrong and had to be protected at all costs. When Russell and Vince spoke to their grandmother about their father’s crimes they were told that it was a family secret, which they were forbidden to talk about. ‘“He’s my son,” my grandmother said and that dogma took precedence over absolutely everything. It was non-negotiable,’ Russell explained to me.

‘My grandfather is not without blame either – in fact, he was more wicked than my grandmother. He killed federal agents during the Prohibition in 1920–33, who were searching in the mountains of Oregon and Idaho for people making illegal whisky. He was never caught for killing, but he did serve time for forging a cheque, taking a woman over state lines for immoral purposes, and for beating a prison guard almost to death when he was escaping. He used to tell Dad horrible things about my grandma after they divorced. My grandparents’ influence was a textbook catalyst for creating a psychopathic serial killer.

‘It was common knowledge throughout my family that Dad had killed our mom in September 1968. When the Justin B was anchored that memorable night off Belize City and he intended to kill Vince and I the next day, he told us how he had killed Mom, but my grandmother had already told me when I was seven. She wasn’t one to sugar-coat things – she was an odd one and would talk about anything and everything. She said she needed to tell us so that it was no longer a mystery and because she didn’t want us to think that our Mom had abandoned us. Dad, however, gave us more details. I remember Vince having terrible nightmares after Belize.

‘After Dad killed Mom, he sought help from his aunts (Grandfather’s sisters, Grace and Mildred), and they removed Mom’s clothing and personal items from her apartment and took them to a local thrift store to make it look as though she had left. Dad came to my grandmother’s house in Roseville the day after he killed Mom. Divorced from my grandfather, she was married to a man named Mark Sellers. Mark spotted the blisters on his hands and said, “Duane, what happened to you?” Dad started crying and told him what had happened. Mark said: “Don’t tell your mom, it will break her heart,” so initially they lied to my grandmother, saying that my mom had left.

‘My grandmother couldn’t understand why Mom would just leave like that because she knew she loved us. Mark kept sending her on wild goose chases, saying: “Oh, I saw Mary Lou working at this store over there,” and my grandmother would drive over and frantically look for her. After several months, my grandmother said: “Duane, what happened to Mary Lou?” He finally told her. It was then that Dad gave my grandmother my mom’s box of jewellery, high school scrapbook, mementos, drawings and photos.

‘Wanting to know more about my Mom, I spoke to my greataunt Grace but she said she didn’t know much about it and then clammed up completely. I knew she knew but I didn’t want to hold an old lady’s feet to the fire so I stopped asking her about it. I also asked my grandmother why my Mom’s murder was kept a secret within the family and told her that, had she reported him, he might not have gone on to kill others, but all she said was, “We’re family, we don’t talk about it, Russell.”

‘Within days of Mary Lou going missing, a missing persons report was filed with the Sacramento Police Department by her younger brother, Jeffery Venn, who told authorities her disappearance seemed particularly out of character given “she was a devoted mother to her three children and could not stand to be away from the children for any period of time”.’ Jeffery told police that Boston was acting uncharacteristically ‘nervous and jittery’ and said he didn’t want to get involved if Jeffery contacted the police.

The missing persons report also noted that a .22 calibre rifle with a scope, said to be Boston’s favourite possession, was missing. Boston told Jeffery he had traded it in: ‘For some junk items he wanted’. Jeffery reported this to the police plus the fact that a couple of shovels in the back of Boston’s truck had fresh soil on them. He told them that when he himself had questioned Boston about them, he explained it by saying that he had lent the truck to some friends to go deer hunting. Boston had never lent his truck before and he was not the sort of person to lend anything to anyone, said Jeffery.

Mary Lou’s mother, Helen Venn, was also interviewed and she described how her daughter was just eighteen years old when she and Boston had run away to get married. In further incriminating testimony, she said that she didn’t like or trust her son-in-law. She complained that he avoided work but always had money and he would spend it on himself and not his three children. Most damning of all, she said that he had threatened to ‘blow her head off’. Despite all of this highly compelling evidence, quite shockingly their accounts were discredited and police investigators concluded that Mary Lou Boston’s disappearance: ‘Does not appear to be a legitimate missing person case because the couple are having marital difficulties and the wife has left the husband’.

‘They even threatened to charge Mom’s brother, Jeffery, and her parents for harassment if they kept bothering the police. Jeffery later committed suicide supposedly because he never got over the loss of his sister who he was close to,’ says Russell.

Boston worked at this time as a driver for two different ambulance companies including the Metropolitan Ambulance Company in Los Angeles County. Vince recalls: ‘I know that he collected a lot of photographs from dead people. Like this guy hung himself from a tree in his backyard and he had his tongue sticking out and my dad would keep all of those pictures in a scrapbook and show them to us kids. It was full of his gore and stuff.’

Both Russell and Vince are naturally dismayed at how the Sacramento Police Department in 1968–70 comprehensively botched the investigation into their mother’s disappearance to the point of absolute negligence.

Russell says: ‘So many times, the police could have, and should have, stopped him. I still don’t know why it took so many decades to connect the dots about my father.’

Vince says: ‘The almost non-existent way in which they “investigated” my mom’s murder was a travesty. If they had properly investigated and locked Dad up then, he wouldn’t have been free to destroy all the lives that he subsequently did.’

He added: ‘Mom’s family used to send us letters and gifts but Dad had left explicit instructions not to let them contact us. My grandma and my dad had a weird bond and they would fight over our welfare money. One time when he was extremely drunk, he came to pick us up from her house but we weren’t there, so he kicked in her glass door. She made him pay for that when he sobered up. She was pretty tough and they would get into big screaming matches. I found letters that he wrote to her over the years. He would say: “I miss you so much, Mom”. Really nice sweet letters, but when we were around he would call her a “cunt” or a “bitch” but I don’t think she was ever in fear that he would kill her. She would always cover for him. She put us in Sunday School and was a Christian and didn’t want him to do these things but knew he was a law unto himself.

‘My grandparents were divorced and Dad would run away from home a lot and run to my grandpa’s house, to whom he was close. My grandpa knew what was going on and basically groomed him to be a criminal.’

Just how shockingly complicit Boston’s parents were in their son’s crimes was revealed during the investigation. In spring 2016, Russell gave Detective Amy Crosby a key to the mobile home that his grandmother had left him when she died in 2009. Seeing if she could glean any further evidence, she made a truly remarkable discovery. Taped to the back of a drawer in Russell’s grandmother’s bathroom cabinet, Amy found a letter in her handwriting, dating from 1978 and addressed to both Boston and his father. The grandmother had concocted an alibi to give to the police if they were questioned about Boston’s nefarious crimes. It mentions Chris and Peta but also, the German/Scandinavian couple that Boston called ‘Vikings’, whom he had boasted to Bryan Logsdon on their road trip in Mexico, he had killed off Dangriga (Stann Creek) by slitting their throats, just weeks after killing Chris and Peta.

The FBI took this very seriously, particularly after Russell found a small scrap of paper in amongst Boston’s belongings from Belize with a German address on it. The FBI in Sacramento instructed its agents in Berlin to investigate if any German, who had travelled in Central America in 1978, had been reported missing. The search identified three possible people. They did indeed trace a German citizen who was in that region at that time but the FBI was unsuccessful in linking Boston to the murder of any Europeans beside Chris and Peta.

It is Russell’s belief that the address on the scrap of paper belonged to one of the many German tourists who travelled on the boat before the ‘Vikings’ were passengers, but it did not pertain to the couple that Boston killed. The fact that the ‘Vikings’ are included in his grandmother’s alibi, along with Chris and Peta and his Mom, leads Russell to believe, that his father killed them. If that is the case, there is some family in Germany, or possibly Scandinavia, whose loved ones never returned and they never learnt of their fate. For all we know there might be relatives of other victims who, like us, have spent decades searching but weren’t as fortunate as us in getting answers.

‘My grandmother was more than just negligent, she was complicit in Dad’s crimes,’ says Russell. ‘She partially helped to raise us, to keep us out of foster homes, and I am grateful for that, but if she and other family members had gone to the police in regard to my Mom, the world would be a much better place.’

Not only did Boston’s parents fail to instil any morality and ethics in their son, they sheltered and protected and aided and abetted him. Between the pair of them, they were highly instrumental in moving Russell and Vince around so that the police could never question them about events in Belize. They have to take a large share of blame for the evil misfit Boston turned out to be and for helping him avoid capture for almost all of his life.