“I won't do anything until I see a photo that O'Neil is OK,” Jorge wrote back. The next morning, someone spotted O'Neil's car, parked downtown and filled with trash and beer bottles.

As Donnie and Jorge watched state police dust the car for fingerprints, an officer pulled the American aside to say he had a bad feeling about Jorge.

To take his mind off his brother's disappearance, Donnie walked among the thousands of partygoers with their faces painted like skulls before ducking into a restaurant to call a kidnapping expert.

“If you're continuing to be hopeful, don't,” the expert said after Donnie told him the kidnappers had gone quiet.

Soon they bought a house together in the District, fixing it up in the evenings. And even after their breakup, after O'Neil moved to Mexico and Brian moved to Maryland, they remained good friends. The same charisma that had made him the centre of attention as a kid in Chevy Chase, Maryland - leading his little brother Chris and their friends through Rock Creek Park, refereeing fights after school at Blessed Sacrament, captaining dodgeball games - made him popular in the gay-friendly resort town.

But to O'Neil Mc Gean, who stood in the Pierce Funeral Home parking lot in Manassas, Virginia, gripping a friend's hand and fighting back tears, Brian had been so much more. They had met at a stoplight, O'Neil's personality so boisterous it took him only a few seconds to make a lasting impression. O'Neil had moved there in 2006 after visiting a few times.

He even suggested suspects to police, organising a stakeout at a property where he said O'Neil might be held, Donnie recalled.

O'Neil had been a popular figure in Mazatlan, donating money to local causes and hosting events at his cafe, so his disappearance was major local news.

On 31 October, Donnie's fourth day in town, he and Jorge went to meet the mayor.

Carlos Felton told Donnie he'd spoken that morning to the governor, who had made it clear he wanted the case quickly solved.

“A lot of these guys were very afraid that this would affect their tourism, would affect the cruise ships,” Donnie later recalled. “We told Jorge a family member has to sign off on the investigation.” The next day, when Donnie returned to talk to Flores, the prosecutor barred Jorge from entering the room. Jorge must have been trying to reach the kidnappers to negotiate O'Neil's release, he thought.

The same day, Donnie met with the prosecutor handling O'Neil's disappearance. He then showed Donnie a diagram of communications between the suspected kidnappers. The next day Mazatlan was packed with people celebrating the Day of the Dead.

A week later, O'Neil stood in front of his ex's casket wondering what had gone wrong. His two cherished dogs - Brandy and Guinness, named after O'Neil's favourite drinks - hadn't been fed. Hope he is OK, wherever he is,” Jorge wrote in broken English. “Our family is very grateful to have you as a friend of O'Neil.