Ms. Dingley was last seen on Nov. 22 on Pic de Sauvegarde, a mountain in the Pyrenees along the border with Spain, according to the French authorities. She had planned to return three days later, Mr. Colegate said.
By early December and amid poor weather conditions, the authorities in France had grown pessimistic about the chances of finding Ms. Dingley. That month, Mr. Colegate said his partner’s disappearance had “broken” him.
In the months that followed, Mr. Colegate pursued his own search efforts alongside the French and Spanish authorities, zigzagging across the mountainsides surrounding Ms. Dingley’s last known location and her known route. “I’ve walked about 700 miles now and also found no sign of her,” he said in a statement on Facebook this month.
Writing about his exhaustive search efforts for the BBC, Mr. Colegate said his partner’s vanishing had “defined almost every waking moment for me for more than seven months now.”
He said that when friends suggested his search was like looking for a needle in a haystack, he disagreed with the comparison.
“Even if the analogy did work,” he wrote, “my response would be that you can find a needle in a haystack, if you’re willing to study every strand, one at a time.”