JAY Slater's distraught dad has been left baffled by a crucial detail during the desperate search for his missing son.
Warren Slater, 58, said "it doesn't make sense" that Jay ended up trekking through the mountains.
Jay, 19, was last seen three weeks ago on the morning of June 17.
He left an Airbnb on the north-west of the island and was spotted heading towards a rural area of parkland near a huge, rocky ravine.
Police, firefighters, volunteers and mountain rescue scoured the area known to locals as "the badlands" in an attempt to find him.
But Warren said he "can't understand" why his son would have strayed off a road and into the dangerous valley.
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Now leading the search himself, the worried dad said they've scoured 80 per cent of the ravine in question.
He told The Sun: "All I'm thinking is common sense, would you try and walk through there.
"Where we've been today you can see there's a hikers path with proper stones. We've gone straight down and you end up in the village.
"I'd go into the first building you see."
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After police, firefighters, volunteers and mountain rescue spent a fortnight looking for Jay, they axed the active search on June 30.
Now his distraught loved ones, who flew out to Tenerife the week he vanished, are retracing his last known steps themselves.
"It doesn't make sense, he's either hid himself, but why would he hide himself? Or he's just ....?" he added to The Mirror.
And after a week of scouring the mountains region of Masca, Warren has said the family are expanding their search area.
Explaining the decision, he told The Sun: "I’ve been through 80 per cent of the valley, so we went further along.
“We’ve done the valley where his phone pinged. We’ve been on two wild goose chases to abandoned buildings."
Warren has questioned why anyone would choose the thick vegetation over a safer, more obvious route.
He told The Sun of the ongoing search: "Now, we’ve gone up the road to a vantage point, there’s cliffs there and there’s a valley and a village there.
"Where we’ve been today you can see there’s a hikers path with proper stones. We’ve gone straight down and you end up in the village."
Yesterday Jay's family focused their efforts in the town of Santiago del Teide which made headlines several weeks ago, reports.
Jay's mum Debbie Duncan told press on Saturday June 22 that a witness went to cops and claimed to have seen Jay in the village the day he disappeared.
They apparently said he was with a pair of men sitting on a bench outside a church, 3.5 miles away from his last known location.
The mysterious sighting raised questions as the witness placed Jay there at 6pm, some nine hours after he was last heard from on Monday morning.
On Wednesday June 26 The Sun revealed exclusive CCTV footage that showed police scouring the town.
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An officer with a torch and another man were seen combing the area for clues, at one point examining a red container.
The pair then walked towards the town hall, before heading back over to the church and waiting near the road.
THE MYSTERIOUS CASE OF JAY SLATER
By Ellie Doughty, Foreign News Reporter
Monday July 8 marks three weeks since Jay Slater, a 19-year-old from Oswaldtwistle, Lancashire, vanished in Tenerife.
The apprentice bricklayer, who flew out to the popular holiday island for a rave festival with friends Lucy Law and Brad Page, has made headlines around the country.
On Sunday June 16 the three of them headed off to one of the events at Papagayo nightclub.
In the early hours of Monday 17 - Lucy and Brad were ready to head back to their hotel, but Jay wanted to keep partying.
It was then that he left the south of the island and headed to an Airbnb in the northwest with two British men.
The Sun revealed the identity of one of them - convicted drug dealer Ayub Qassim, who spent nine years behind bars in the UK.
For days it was thought that the second mystery man went by the name ‘Johnny Vegas’.
On Sunday former detective Mark Williams-Thomas, who is out in Tenerife investigating, said Qassim told him he is in fact the man behind the nickname ‘Johnny Vegas’.
We don’t yet know the identity of the second man - who remains a key part of the puzzle in Jay’s mysterious disappearance.
Qassim claims he drove Jay and the friend back to their accommodation and said they all went to sleep.
In the morning he offered to drive the teen back to the Los Cristianos resort after a nap, but Jay, hungry and tired, said he wanted to leave immediately.
Lucy, the last person to speak to Jay, claims she had a panicked call from him soon after he left the holiday let, telling her he was lost and thirsty, his phone was about to die and that he’d been cut by a cactus.
Jay had been seen by the owner of the Airbnb that morning wandering around near the Rural de Teno park - a mountainous region close-by.
He is believed to have been attempting the 11-hour trek back to his hotel, despite the alleged offer of a lift and more buses scheduled for the day.
It was there that his phone last pinged - and he hasn’t been seen or heard from since.
Mark Williams-Thomas has claimed he left the Airbnb quickly, and was “scared”.
Bizarrely, Qassim says he was woken up that morning by a phone call from an unnamed friend of Jay, saying he was “in a ditch” somewhere and had been “cut by a cactus”.
Jay’s friend Lucy claimed to have “tracked down” the two men in the Airbnb after he vanished - quizzing them on the morning of Jay’s disappearance.
Some reports have suggested Lucy knew the two men, although it is not clear how.
She has dubbed his disappearance “weird and suspicious”.
Both men were questioned by Spanish cops on June 17 but quickly deemed “irrelevant” to the investigation and cleared to fly back to the UK.
Police spent almost two weeks searching for Jay in the Tenerife mountains, scouring a 2,000ft ravine, before calling it off on Sunday June 30.
Jay’s family have repeatedly slammed the Spanish investigation into his bizarre disappearance.
His uncle, Glen Duncan, is convinced of “third party involvement”.
And the teen’s devastated dad, Warren Slater, says “everything stinks”
He told The Sun: "My starting position, I’ve said this from day one, ask the two men who’ve taken him - and then start from there."
A number of unanswered questions remain, over why Jay would have travelled so far with two older men he didn’t know, why said men would have taken him in, and why he braved the Tenerife mountains with no phone battery, water or heat protection for a day-long walk.