On 10 July 2024, the England footballer Ollie Watkins scored a last-minute winner against the Netherlands to secure the Three Lions’ place in the Euro 2024 final. It was a balmy evening and joyful fans left pubs up and down the country elated and relieved that England had made it to the final for the second successive Euros.

Among them was 61-year-old Giles Malone. He was waiting for a taxi outside the Mall pub in Clifton, a leafy, affluent suburb of Bristol, when he spotted two men grappling with a suitcase.

“I said to them: ‘That looks really heavy; what have you got in there, a body?’ – jokingly like you do,” Malone later told reporters. He was partly right.

The suitcase contained the parts of not one but two bodies. And one of the men was their killer, Yostin Andres Mosquera. It was not until the next morning that ripples of rumour started to spread through Bristol and its surrounding villages. Clifton Suspension Bridge, the city’s emblematic landmark, was closed both ways. A police tent had been erected at the western end.

Closure of Isambard Kingdom Brunel’s masterpiece both ways is rare but not unprecedented; residents speculated that perhaps someone else had taken their own life or someone had been knocked off their bike.

Later on the 11 July 2024, Avon and Somerset police released a statement that shocked the community: a suitcase containing human remains had been found on the bridge and the suspect seen handling the baggage was at large.

Before Mosquera was arrested two days later, a video obtained by the Sun taken by a cyclist appeared to show the rider confronting the suspect as he ran away from the bridge through the area of Leigh Woods in North Somerset.

It was reported that the fleeing suspect could be heard saying in Spanish: “My boss is a bad man,” prompting speculation that this might be a gang-related murder.

But the circumstances of this murder were much more singular and unexpected.

The two victims were Albert Alfonso, 62, and Paul Longworth, 71, who were in a civil partnership and lived more than 100 miles away in Shepherd’s Bush, west London. They were easily tracked: the suitcase containing their body parts had a label with their address attached.

It was not until the trial at the Old Bailey in London opened this year that the nature of their relationship with Mosquera emerged.

Alfonso liked extreme sex, which Longworth knew about and accepted but had nothing to do with. Alfonso met Mosquera, a Colombian national, via webcam sites around 2012 aimed at his sexual preferences. Prosecutors described Mosquera as a “pornographic performer”.

During his defence, Mosquera told the court he had met Alfonso in person in Colombia in 2022 and 2024. Photographs shared online by the couple show Alfonso and Longworth with Mosquera on holiday in Colombia, smiling and apparently enjoying each other’s company.

But on 8 July 2024, while Mosquera was staying with them, he murdered the men. Alfonso’s killing was filmed on camera. Alfonso, a swimming instructor, was stabbed to death while the two men were having sex, with both the sex and murder recorded on film.

Longworth, a retired handyman, was attacked with a hammer to the back of his head, suffering repeated blows, which shattered his skull.

After killing Alfonso, Mosquera used the victim’s computer to look at banking information relating to the couple, before compiling a PowerPoint document of that information. He then tried to send £4,000 to his own account in Colombia, before going to a cashpoint and withdrawing money.

Analysis of the defendant’s computer revealed that between June and 8 July he searched for the value of the couple’s west London home, browsed Facebook Marketplace for a chest freezer, copied spreadsheets containing Alfonso’s login details for his online bank accounts on to his laptop and searched for “serial killers of London” and “Jack the Ripper film”.

After dismembering the men, he put their heads in the freezer before transferring the rest of them to a suitcase and taking it to Bristol.

Mosquera claimed that it was Alfonso who killed Longworth, and that he feared for his own life and believed he was about to be killed when he stabbed Alfonso.

But the jury were not convinced.

The Metropolitan police’s DCI Ollie Stride, who led the investigation, told the Guardian it was “one of the most harrowing murders” his team had ever investigated and would stay with them “for a long time”.

“The team have consumed hours of footage, much of it of the utmost disturbing and graphic nature,” he said. “Those images will stay with all of us for a very long time.”

Stride said the case had presented unique challenges, with a “vast amount of digital media” to review, much of which was in Spanish, requiring translation. They reviewed hundreds of hours of CCTV, and conducted extensive forensic analysis to build the case.

It is understood Mosquera had a wife and two children in Colombia. Authorities in the South American country found only two minor matters more than 10 years old on his criminal record, as well as two minor traffic matters.

“We are in no doubt he may have amassed a following online due to his sexual endeavours, but we are confident he worked alone and there are no accomplices with relations to the murders,” Stride said.

The sexual activity in the case has garnered prurient attention but Stride said nothing uncovered was illegal. “There has been a lot of focus on the sexual activity in this case,” he said.

“Whilst it may be unorthodox to many, it was legal, consensual sexual activity in their own home. There were additional challenges for the investigation, particularly in securing the trust of those who are not openly involved in this activity.”

Despite Mosquera’s apparent warning that his “boss was a bad man”, the Met found no evidence of any accomplices or others directing his activity through the investigation and nor was this a defence Mosquera relied upon.

As for why the murderer chose one of the most famous landmarks in the south-west of England, visited by thousands of tourists, as well as a key route in and out of north Bristol, to dispose of the bodies – that remains a mystery.