The apprentice bricklayer, from Oswaldtwistle, had been attending the NRG music festival on 16 June, and his friends said they were out in the tourist hotspot of Playa de las Americas when he was seen getting into a car with two British men he met earlier in the night.
The next morning, 17 June, he was tagged in a photo posted on Snapchat at 07:30 BST at an Airbnb in Masca, which was reportedly being rented by the two men.
Investigators have spoken to the pair and they are “not in any way relevant to the case”.
He was last heard from before 09:00 BST in the Rural de Teno Park, where he called a friend to say he had missed the bus and was trying to make the 10-hour walk back to their accommodation in the south of the island.
Lucy Law said Mr Slater told her during a frantic phone call that he was “lost in the mountains”, desperately needed a drink and had 1% battery on his phone.
Best friend Brad Hargreaves told ITV’s This Morning he received a video call from Mr Slater around the same time in which he appeared to be sliding off a designated path, with the call showing his feet on rough ground.
Speaking to ITV last week, Mr Hargreaves said: “I don’t know how or what has gone on there but he’s gone off and rang me halfway to their house saying I’m staying here and I’ll be back the next day.
“He’s rang me walking down the mountain and he just says he’s walking home.
“At the time I didn’t think anything of it I just thought he was going to get a bus home or a taxi home because that’s what he says he is going to do.
“Next thing you know his phone dies and it’s 10 days on now and nothing since.”
A GoFundMe appeal Get Jay Slater Home, set up by Ms Law, had raised more than £43,000 as the police search came to an end.
Mr Slater’s mother, Debbie Duncan, travelled to the island as the search took place.
She said the money raised online would be used to support mountain rescue teams, and to cover her own accommodation and food costs.
Speaking to the BBC previously, Mr Slater’s mother said: “He’s just an all-round nice, bubbly guy with hundreds of friends who love being in his company,” she said.
“He’s gorgeous, he’s beautiful. He’s my baby.”
Lancashire police referred BBC questions about the cancellation of the search to the Guardia Civil, saying its role was to support Mr Slater’s family.