Police say they now believe 70-year-old Robert Saint, who vanished while trying to sell his boat, was murdered and his body dumped overboard.

Detectives investigating the disappearance of retired businessman Mr Saint said the discovery of his wallet on a beach on the Isle of Wight suggested he had been on the boat.

The 42ft motor cruiser, called Sundowner, was last seen leaving Birdham Pool near Chichester last Thursday.

Mr Saint, of Horsham Road, Steyning, had driven to the harbour to meet a prospective buyer, who claimed to have the £119,000 asking price in cash.

Sussex Police were unsure whether Mr Saint had boarded the vessel, which was later found moored at nearby Itchenor with no sign of the pensioner.

But now the discovery of the wallet and personal papers thought to have belonged to Mr Saint has prompted detectives to say he was almost certainly murdered on the boat and his body dumped at sea.

A search of the Sundowner, carried out at Chichester Harbour, found blood in the galley. Tests are continuing to determine whether it was Mr Saint's.

And today police said bloodstained clothing thought to belong to the killer was also found on the boat.

Detective Chief Inspector Tony O'Donnell, leading the investigation, said: "Finding what we think is Robert's wallet in this way is a significant development, although sadly it adds weight to our fears that he has been murdered.

"It is possible of course that some of Robert's other possessions could also be washed ashore.

"We've found a bloodstained shirt that we think belongs to Robert's murderer. We've sent the shirt for forensic analysis, and meanwhile we're renewing our appeal for the public to come forward with any information that could help us solve this case."

Mr Saint's wallet was spotted by a woman on a beach near Bembridge. She picked up papers lying nearby to hand in to police but only realised the significance of the find when she returned home and saw media coverage of the murder inquiry.

The woman left the wallet on the beach but an extensive police search has now recovered it.

It is a week since Mr Saint, whose wife Pamela died earlier this year, drove to Birdham Pool with the intention of selling Sundowner.

A cheque from the buyer had bounced, police said. They described the proposed cash deal as "highly suspicious".

The boat is believed to have left Birdham at about 1.30 pm on Thursday, September 26.

Detectives continue to appeal for sightings of Mr Saint, who worked in the timber industry, over the past week, and to anyone who may have seen the boat at sea. It is thought to have travelled as far as Portsmouth.

A 44 year-old man from Bognor, who was being questioned by police, was released without charge on Tuesday afternoon.

The same day, family and friends of Mr Saint appealed for anyone who had any information about his disappearance to come forward.