Witnesses report hearing a "thud" as police arrested a man later found with a massive brain injury in a cell.

Garry Reynolds, 39, has been in a coma in hospital since March 2.

His brother Graeme yesterday won a vital round of his bid to see Sussex Police removed from the investigation into what happened to him.

A High Court judge is expected to rule next week that the Independent Police Complaints Commission (IPCC) has the power to take over the inquiry.

Until now, events leading up to the arrest were being examined by Sussex Police, while the investigation of the arrest and subsequent events came under the remit of the IPCC.

Graeme Reynolds launched a legal bid to take the inquiry completely out of Sussex Police's hands.

The events of the night of March 1 are still under investigation but what is known is that Garry left a party at the Rock Pub, Rock Street, at about midnight.

He was picked up by a taxi driver more than an hour later. What happened in the intervening period is unknown.

The taxi driver became concerned he would not pay the fare and called police. It was at that point Garry was arrested after police said he became aggressive.

Mr Justice Collins told London's High Court that witnesses reported hearing a 'thud' as Garry was surrounded by police, but exactly what happened at the scene is still being investigated.

Graeme Reynolds's barrister, Sam Grodzinski, told the court: "When Garry Reynolds was found in a coma, the IPCC should immediately have been called in, and from the outset, taken responsibility for the investigation."

Richard Perks, representing the IPCC, argued in court documents: "It is suggested that Mr Reynolds' faith in the investigative process has been damaged and that this is a reason for making the order he seeks.

"While that may be unfortunate, it cannot dictate police procedure".

Mr Justice Collins ruled that the IPCC was wrong to consider they had no power to investigate what happened before Garry Reynolds' arrest.

He told the court: "What matters for the purposes of this investigation, is whether he sustained the injury when he was arrested, or whether he sustained the injury before he was arrested.

"If it was not before, then the police are responsible, if it was occasioned before, then the police are not likely to be responsible."

The judge said he would give full reasons for his decision later, in writing.