British Teenager’s Disappearance Spurs Speculation and Sleuthing

When a young British man disappeared while vacationing on the Spanish island of Tenerife in mid-June, a familiar routine unfolded: search and rescue workers combing through the landscape, regular updates from tearful family members, a steady drumbeat of unconfirmed reports that he had been spotted.

And soon after, they were joined by another increasingly common feature of disappearances: online sleuths who are certain that they can do what the police have not yet done and solve the case.

This weekend, the Spanish authorities called off their search for Jay Slater, a 19-year-old apprentice bricklayer from England who was visiting Tenerife, a popular vacation destination. But even after the 14-day search officially ended, conspiracies and other theories have continued to spread online.

“There’s a small minority that believes and engages with these things,” said Aleksandra Cichocka, a professor of political psychology at the University of Kent. “But they can be really disturbing to the family and the whole process of the investigation.”

Mr. Slater attended a music festival on the island with a friend, according to a statement from his mother, Debbie Duncan, through the missing persons organization LBT Global. On the festival’s final night, Mr. Slater left with two people he had met at the event to go to their apartment in a more secluded part of the island, according to Lucy Law, a friend with him who provided details in an online fund-raising page for his family.

The next morning, on June 17, Ms. Law said Mr. Slater told her on a phone call that he was lost in the mountains, thirsty and running out of phone battery. He called another friend, who told the British news media that Mr. Slater had decided to go down a “little drop” beside a road. That morning was the last time anyone heard from him.