Gary Watson Shearer, from Renfrew, arrived in the resort of Puerto del Carmen on Lanzarote on March 16 last year to celebrate St Patrick’s Day.
The 53-year-old was last seen in the early hours of the next morning, and he then failed to show up for his flight home a week later.
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Now, his sister Debbie, 49, has told the Daily Record that her family are in “disbelief” after Spanish police told her parents they have “exhausted all leads”.
She said: “We are in disbelief. We are angry and we feel let down by the police. We just don’t know how they can do this.”
Gary reportedly disappeared from outside Bar 67 in Puerto del Carmen, however, CCTV cameras show he was lying unconscious in a shop doorway next to the pub at around 1.30am on March 17.
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We previously reported in August that authorities were looking to speak to a mystery man who was last seen walking with Gary on March 17.
He is described as being from 60 to 70 years old, well-built, with grey hair and he was wearing a light brown sports jacket, white shirt, and long dark trousers.
Debbie told the Daily Record: “We do not believe they have exhausted all leads because they have not found the man that they released footage of – who was the last known person seen with Gary.
“We’ve been told he had no interaction with Gary but there must have been something that prompted the police to release that footage in the first place.
“They were the ones that wanted to speak to that man. Why?
“This is why we remain confused. It’s just been the same story throughout the full investigation, just no answers to questions. It’s a nightmare.”
Gary was last seen wearing a Celtic top, shorts, and white Nike trainers with green and yellow flashes.
The much-loved family man is described as being around 5ft 2inch tall, has short hair, and walks with a distinctive limp.
A Foreign Office spokesperson previously told the Glasgow Times: “We are supporting the family of a British National missing in Spain and are in contact with the local authorities.”