A sock was found in the mouth of a man whose naked body was washed up on a beach, police have revealed.

Alan Eric Jeal, 64, was found at high tide at 2pm on 25 February, on Perranporth beach in Cornwall. He was only wearing socks and one walking shoe when his body was discovered by a dog walker. He was identified after relatives recognised an artist's impression issued by police.

A postmortem examination found multiple injuries on Jeal's body that were inconsistent with drowning. Police are treating the death as suspicious.

DCI Dave Thorne, senior investigating officer at Devon and Cornwall police, said he could not explain why the sock was in Jeal's mouth. The officer added: "This is one of the reasons we are treating Alan's death as suspicious … Murder is one possibility we are considering. However, his death may have been caused by accident or suicide."

Detectives have released a map and a series of CCTV images showing a man, believed to be Jeal, in the centre of Truro the evening before his body was discovered.

It is believed Jeal, who lived alone in Wadebridge and was not reported missing, took the number 594 bus to Truro, arriving at the bus station at 6.14pm.

He was seen walking towards the public toilets at The Leats and was last seen at 6.36pm in Boscawen Street. Officers are trying to establish where Jeal went after that and how he travelled to Perranporth, and have appealed to the public for help.

Police previously released a series of photographs of items found on Perranporth beach near where his body was discovered.

A Regatta jacket, wallet and a photograph of a young boy – believed to be Jeal aged two in his family home – are thought to have belonged to him. It is not known whether a woolly hat and a rucksack were his.

Speaking after his death, his family released a statement paying tribute to him.

"Alan was a mild-mannered, gentle man who was very interested in minerals, mining and surfing," they said. "We are shocked and deeply saddened that Alan's life has been cut short, and are desperate for answers as to what happened. "We appeal for anyone with information about Alan's life and last movements to contact police."