Detectives investigating an horrific Christmas Day attack say the solution to the case may lie in the victim's past.

Christian Bowles was beaten unconscious and left lying in a pool of blood on waste ground next to a derelict building.

Nearly three months later, police have admitted they do not have a named suspect or motive for the assault in Preston Road, Brighton.

The investigation is now focusing on Mr Bowles's personal life and history to see if it can provide clues to the motive or identity of his attacker.

On Christmas Day afternoon a man in his 40s - who has still not been identified - arrived at the camp next to Anston House where a group of people were claiming to protest against the destruction of trees by developers.

The man specifically asked to see Mr Bowles. The pair got into an argument.

What happened next is not clear, but by 6pm Mr Bowles had received the massive head injuries which kept him in hospital until earlier this month. DI Carwyn Hughes of Brighton CID said finding the man is the top priority of the investigation.

He said: "We have two people who state that a person came to the Preston Road site looking specifically for Christian.

"Despite numerous enquiries and forensics, that person has not been identified.

"To identify that person is a major line of enquiry which will keep this case alive."

The man is described as about 5ft 6in, of thick build with shortcropped brown hair and clean shaven. Search teams spent three days combing an area of hundreds of square yards. They recovered hundreds of pieces of evidence including metal, glass and porcelain.

Police have still not revealed details of the weapon they believe was used to inflict Mr Bowles's injuries.

They are describing it only as an "edged instrument".

They are holding the full description back in case they eventually question the culprit.

DI Hughes said: "It could be incredibly important one day."

Two men were arrested on Boxing Day in connection with the attack. The first, a man in his 40s, was released on police bail but has since been ruled out of the investigation.

The other man, in his 60s, was never detained on bail.

DI Hughes said: "Having reviewed the forensics, I am not in a position to charge anybody."

Mr Bowles's head wounds left his right arm and right leg permanently damaged.

He spent a week in a coma at Hurstwood Park neurological centre before being taken to Southlands Hospital in Shoreham for rehabilitation treatment.

His mother Jill told The Argus: "We know the police are doing all they can and we hope the attacker can be brought to justice soon."