The rollercoaster of emotions, so much a feature of this case from 1978, still had some more unexpected twists and dives. With our hopes buoyed at the imminent prospect of going to California to give pre-trial evidence, we were then hit by another tsunami of disappointment.

Boston failed to appear at the status hearing on 14 February 2017. Unbeknownst to the prosecution team, he had fallen ill the day after his last court appearance on 27 January and was hospitalised, due to apparent complications from heart and liver disease. Boston’s attorney, Lexi Negin, said she was informed by Sacramento County Jail officials that Boston had been hospitalised for nearly two weeks for ‘a very serious condition’, adding: ‘We are unsure if he is talking or conscious.’

Jail authorities wouldn’t reveal where Boston was being cared for, but he was reported to be suffering ‘complications of liver failure and congestive heart-failure’. Giving us some ray of hope, Negin said that Boston’s condition might not be life threatening: ‘he could be back in jail in a few weeks.’

In a written motion, Matt Segal requested that the depositions be taken in open court, arguing: ‘There is no better evidence than sworn, cross-examined testimony taken under court supervision. Given the witnesses’ current ability and willingness to travel, there is no practical reason why their depositions cannot be taken under the conditions that the law most favours.’

Boston’s defence attorneys argued that any pre-trial depositions should be conducted in private and not introduced into the record until the trial began.

Because Boston wasn’t in court, District Court Judge John A. Mendez said he was unwilling to rule on the prosecution’s motions to grant permission for pre-trial depositions and to allow them to be held in open court. He scheduled a hearing for two weeks time on 28 February 2017 to get an update on Boston’s medical condition and consider an anticipated motion by prosecutors to allow the depositions even if Boston couldn’t be present in court.

He concluded: ‘I understand your concern for the witnesses and the mother of the victim. I understand what is going on here. Both sides have serious needs.’

Out of hospital, Boston returned to federal court on 28 February and we were delighted to hear that the judge sanctioned us, plus David Sacks and the Guatemalan pathologist, Dr Angel María Vásquez Cuéllar, to go to California to give depositions in April or May.

The judge agreed that the prosecution team could interview the witnesses and record their testimony for potential introduction for trial and the defence was allowed to cross-examine us. The depositions were to be conducted at a location to be determined by the lawyers and a federal magistrate to be available to answer procedural questions by phone but not physically present. He set a potential trial date for seven months hence, on 2 October, but said he was uncertain whether the case would be ready to begin with jury selection by then.

Boston was described as having a pungent smell because since entering jail he had displayed a reluctance to wash, apparently a not uncommon trait of prisoners wanting to make themselves even more objectionable. He was equipped with headphones to help his hearing, but complained that he was having trouble following the discussion.

‘Were you able to hear me, Mr Boston?’ Mendez asked.

Boston nodded to the judge, but indicated he couldn’t hear his attorney, Lexi Negin: ‘I couldn’t hear her,’ he said, fumbling with his headgear. ‘Hello? Hello?’

‘He is taking a lot of medication,’ Negin said. ‘Mr Boston is good today. I don’t think there is any issue today. But it is an ongoing medical issue.’

6 May was set as the date when the UK contingent were to travel to California, accompanied by Martin and Michaela, to give our pre-trial evidence. We eagerly anticipated the day arriving when we would be stepping off the plane in Sacramento. It was a surreal concept to grasp that we were now within weeks of coming face-to-face with Chris and Peta’s killer.

But the rollercoaster hadn’t stopped turning - the unthinkable happened. Boston, who had turned seventy-six on 20 March, took a grave turn for the worse. On 5 April, he had started to refuse his medication and treatment and by mid-April, he was re-hospitalised in a far more serious condition than in February.

Suffering liver and heart complications, Boston, dressed in the distinctive orange boiler suit reserved for high-security prisoners, was moved from Sacramento County Jail to the City’s UC Davis Medical Center in the presence of two burly armed guards.

‘There has been more dire information about this hospitalisation,’ Boston’s Defence Attorney Negin told the court on 19 April. ‘If he weren’t in custody, he would probably be referred to hospice care.’

We were totally shocked and dismayed to learn that the defence team then filed a ‘declaration of doubt’ that Boston was competent to face trial, suggesting his health was fast deteriorating, impairing him both physically and mentally.

‘The Court finds that reasonable cause exists to believe that Mr Boston may presently be suffering from a medical condition that has caused a mental disease or defect rendering him mentally incompetent to the extent that he is unable to understand the nature and consequences of the proceedings against him or to assist properly in his defence. The Court orders that Mr Boston be committed to the custody of the Attorney General forthwith for placement in a suitable medical facility for a psychiatric or psychological examination and treatment.’

‘The law requires him to be mentally present during court proceedings,’ Judge Mendez responded. ‘If he is in and out of awareness in terms of his medication, he may be physically present, but mentally he is not there.’ He ordered a medical competency evaluation for Boston but the challenge was that Boston would need to be airlifted to a medical facility in the federal prison system as far away as Illinois or North Carolina for an appropriate evaluation. Negin said Boston was in no shape for such an excursion.

Our much longed for, and highly anticipated trip to Sacramento was cancelled. It was crushing. Bitterly disappointed, I wrote the following letter to Judge Mendez imploring his help: ‘To hear the news yesterday that Silas Duane Boston might not be fit to stand trial was nothing short of devastating for us as a family.

‘Since I first made the phone call to Greater Manchester Police with the findings of my internet research and the whereabouts of Boston and his sons, Vince and Russell, on October 5th 2015, the fight for justice for my brother Chris and his girlfriend, Peta, has become an all-consuming personal crusade. To receive this news is therefore a massive blow. If it is that Boston doesn’t stand trial, the ultimate sadness is that the wheels of justice just didn’t move quickly enough for us. It is particularly tragic when, for 37 years, those wheels barely moved at all.

‘This last cruel twist of fate is, of course, nowhere near the pain of losing Chris but it’s a very bitter pill to swallow when we were reaching the last hurdle and a trial was in sight. Mum, in particular, has taken the news badly. It has been a very sad, long journey to this point, but she was more than mentally and physically prepared for making the trip on May 6th in the hope that at the age of 92 she would see her son’s killer brought to justice. When Boston threw, like jetsam, their tortured bodies alive into the waters of the Caribbean he thought they would not be missed. He could not have been more wrong: Chris was a much-loved son and brother as keenly missed today as when he first went missing.

‘I know the Head of the Greater Manchester Police Cold Case Review Unit, Martin Bottomley, and California Prosecution Attorney, Matthew Segal, and their respective teams have done absolutely everything within their powers to bring Chris and Peta’s merciless, barbaric killer to justice and for that, as a family, we are eternally grateful. Leaving no stone unturned, they have, after almost 40 years, quite unbelievably given us knowledge of why they were senselessly murdered. They have all gone the extra mile for us and we are indebted to them. It would be the ultimate tragedy if this case were to falter now.

‘I appreciate that Boston’s state of health is out of everyone’s hands but if anything can be done to bring about a prosecution, please rest assured that my mother and I are ready to jump on the next plane to America without any notice. Our visas are all prepared. If, in the end, Boston holds the ultimate “get out of jail free” card and dies before he faces trial, he will have trumped us all. So near and yet so very far and that truly hurts.’