The body of the 34 year-old was found at around 3am on West Canal Street, near Canal Court, Coatbridge.
Officers have since found CCTV footage of the 34 year-old man walking along West Canal Street around 12.45 am. He was wearing a grey baseball cap, dark jacket and blue jeans.
Detective Inspector Cameron Miller, Coatbridge Police Office, said: “We are currently treating the death as unexplained and are appealing for anyone who may have been on West Canal Street in the early hours of Monday morning who may have seen a man in a grey baseball cap.
“We know from CCTV footage that although it is a quiet street, there were still cars and a few people going about who may have information. No matter how insignificant it may have seemed at the time, it could help us.
“Was he alone? Did he meet up or speak with anyone on West Canal Street? Think back, what can you remember about that night?
“We want to piece together his movements that morning so we can find out exactly what happened to him and get answers for his loved ones.”
Anyone with information should contact Coatbridge Police Office via 101, quoting incident number 0411 of Monday 12 March 2017. Alternatively you can contact CRIMESTOPPERS on 0800 555 111 where information can be given anonymously.