LAWYERS representing a man jailed for murder said last night they would appeal against his life sentence because police had bugged a prison cell to gain the damning evidence against him.

A microphone hidden in a ventilator shaft for three months recorded suspect Mark Graham's conversations in prison.

He was heard saying Mohammed Sharif, 69, was hit "loads of times" and also "all I did is just hit him and he died".

In court, an expert lip reader transcribed secretly-filmed conversations between Graham and his girlfriend, on visits to Holme House Prison, Stockton.

Graham, 24, Jonathan Embleton, 25, and Stephen Ham, 32, were convicted at Teesside Crown Court yesterday of beating the pensioner to death at his home in Garnet Street, Middlesbrough, on April 21, 1999. All three were sentenced to life in prison.

Their frail victim had disturbed the trio as they entered his back yard to steal a washing machine.

His throat was so swollen from kicks and punches that he asphyxiated. The socket of his left eye was broken and he had four broken ribs.

Detective Superintendent Adrian Roberts, who led the murder inquiry, said afterwards: "This has been a most complex and difficult investigation and these verdicts serve as a tribute to the perseverance and professionalism of the team of officers from across the force who, together with the Crown Prosecution Service, brought these men to justice."

The video and audio tapes were ruled as inadmissible by judge Mr Justice Silber at an aborted first trial in June, but were subsequently allowed by the new trial judge, Sir Edwin Jowitt, as evidence for Ham and Embleton's defence.

Nick Woodhouse, Graham's solicitor, said: "We shall be appealing the murder conviction and we shall be citing that the bug was a breach of his human rights."

Graham had pleaded guilty to manslaughter, but the prosecution would not accept it. Ham and Graham, both of Stamford Street, Middlesbrough, and Embleton, of no fixed address, had denied murder.

Following the case Mohammed Riaz, Mr Sharif's son, said: "Justice has now been done and I would like to express my thanks and support for the police, who I know have worked so hard on the investigation over all these months."

Det Supt Roberts said: "Our thoughts of course return to Mr Sharif and his family. This was a senseless killing of a vulnerable old man who was a threat to no one."