Convicted killer Michael Stone has again protested his innocence over the Chillenden murders – this time on a television programme re-examining the case.

Stone, from Gillingham, was found guilty 20 years ago of the horrific hammer attack on Dr Lin Russell and her daughter Megan, aged six, on a quiet country path near Canterbury.

Megan’s sister Josie, nine, was left for dead but miraculously survived the brutal onslaught.

In the first of a two-part documentary, The Chillenden Murders, broadcast on BBC2 last night, Stone claimed he never confessed to a fellow prisoner that he was the culprit.

He added that he had wanted to give evidence at his first trial at Maidstone Crown Court but was afraid he would “lose it” in the witness box.

The programme has assembled a team of independent experts to re-examine the case files.

They have already uncovered information, not presented at either of Stone’s two murder trials, that a psychiatrist treating him had reported days before the killings in July 1996 that he was becoming “increasingly agitated” and had issued threats to kill a probation officer and his family.

Stone, a heroin addict, was 37 and living in Skinner Street when he was arrested. He is serving three life sentences.