Damien Heagney, 47, was last seen between the late hours of 30 December and the early hours of 31 December 2021 in the Dromore area outside Cookstown.
He was reported missing on 19 July this year.
He is described as being around 1.77m (5’10”) tall and of stocky build.
A 50-year-old man has been arrested on suspicion of murder following the search of a property in the Cookstown area.
Detective Chief Inspector Rachel Wilson said: “Whilst I’m keeping an open mind, I now believe that Damien has sadly been murdered.
“Earlier today, Saturday, August 6, we arrested a 50-year-old male on suspicion of murder following the search of one property in the Cookstown area.”
“The man is currently assisting police with ongoing inquiries.”
Police have appealed for anyone with any information surrounding Mr Heagney’s disappearance to contact them.
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