The body of a 57-year-old man has been found near Banton Loch at Kilsyth in North Lanarkshire.
Police have identified him as Alan Brown, and said he had been fishing on the day before he was found.
The last confirmed sighting of Mr Brown was at about 21:00 on Saturday. His body was found by a dog walker at 14:35 the following day.
Police are treating the death as unexplained and have appealed for information.
Det Insp Gordon Sneddon said: “We know that Alan was in the company of friends at the loch on Saturday during the day and then remained there alone after they left.
“There have been several sightings of him on the Saturday evening but it is vital that we piece together his movements between when he was last seen and when he was found dead the following afternoon.
“I would appeal to anyone who believes they may have seen Alan between 9pm on Saturday night and 2.35pm on Sunday afternoon, to please get in touch.”
Mr Brown is described as white, about 5ft 10in in height, with a slim build, short greying hair and stubble.
He was wearing a black jacket with a hood, grey jumper, blue jeans and black trainers.