Christian Butler, 42, set off happily for the first day of a new job in a warehouse on Monday last week, May 23.
He completed his shift but never returned to his Conniburrow home – and nobody has seen or heard from him since.
Christian, who is single and lives with his parents, had left his phone at home and does not appear to have taken any clothes. He drives but does not own a car.
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Family and friends are concerned for his welfare and are desperate to find out what has happened to him.
A friend said: “He is vulnerable. He’s had issues and struggled to keep it together during the Covid pandemic.
"But this was the first day of a new job and a new start and he was happy about it. We just cannot work out what happened and why he disappeared.”
Christian’s family and friends are now working together in a bid to solve the mystery and are asking people to share his photo on social media.
There have been sightings of a man answering his description hanging out in the city centre with a group of people who may have been homeless. There was another potential sighting of a man “passed out” at Teardrop Lakes. But no sighting has been confirmed, said his friend.
If anybody has seen Christian they should call Thames Valley Police on 101 and quote reference number 43220234607.