Two sadistic killers who wrongly accused a man of being a sexual pervert and left him disembowelled alive have had their sentences challenged as "unduly lenient".

Trusting Keith Philpott, 36, who had learning difficulties, was tortured for four hours in his home in Billingham, Teesside, by Sean Swindon,24, and Michael Peart, 22.

The Attorney General has agreed to refer the 20-year maximum sentences to the Court of Appeal after protests from the Crown Prosecution Service.

Swindon believed that he had harassed his sister Gemma,19, and sent her sexually suggestive text messages even though he could barely read or write.

Peart told a pal that Mr Philpott was crying when Swindon ordered him to get on his knees where they bound and gagged him, and kicked and stamped his head to a bloodied pulp before Swindon sat astride him and sawed his stomach with a knife until his insides fell out.

His body was found in the living room of his flat in Billingham, Teesside, when his worried family called police after he failed to appear for tea with his mother Pauline at her home nearby.

Prosecutor Graham Reeds told the judge: "Peart said that he was alive when they left him but he knew he was going to die as a result of what they had done.

"Mr Philpott was particularly vulnerable because of disability and the mental and physical suffering inflicted on him before death."

There was no truth in claims of a sexual relationship with Swindon's sister, who visited Mr Philpott's flat with her friends, Teesside Crown Court was told.

But Peart, who was described by a psychologist as easily suggestible, joined in the attack when Swindon called Mr Philpott a "dirty bastard".

The pair watched him arrive home in Axbridge Court, Billingham, with a bicycle he had just bought, and then they knocked on the door and burst inside when he answered it. Mr Philpott locked himself in the bathroom but Swindon kicked down the door and dragged him out.

James Sunter, a Home Office pathologist, said that Mr Philpott was alive when he was disembowelled and it was probably the cause of his death.

They left stealing the bicycle, his gold ring and a mobile phone. The knife from Mr Philpott's kitchen was never found. Swindon's girlfriend took him to the police next day after, and Peart was arrested days later after he confessed to his best pal David Muldowney.

Peart from Norton-on-Tees and Swindon from Middlesbrough were both jailed for life on October 10 after they pleaded guilty to the 24 March murder.

The Recorder of Middlesbrough Judge Peter Fox QC told them :"This was a terrible killing and must be so marked."

The judge said that Swindon must serve 20 before he is considered for parole, and Peart - who had two convictions for attacks on wrongly suspected paedophiles - 15 years.