A TWISTED monster who doused his mum in petrol and set her on fire hid his horrendous crime from fellow lags - by pretending he was in work fire.
Sources revealed that cons at first felt sorry for William Kelly, 42, at Barlinnie nick in Glasgow.
One said: “He told us he worked with cars and there was an accident with petrol.
“He laid it on really thick, made us all feel really sorry for him.”
But inmates turned on him when they discovered the truth. in devastating ‘arson attack’
The source added: “Everyone was disgusted. What kind of animal does that to their own mother? He was labelled a beast.
“No one wanted to share a cell with him.
“He was alienated from everyone. He took us all for fools, making out he was a victim.”
Sick Kelly was yesterday convicted of murdering his widowed mum Cathy, 71, – despite claiming it was an accident.
He doused his mum in petrol, lit a cigarette over her and set her on fire in her Kilmarnock home on Febraury 11 of this year.
The former off-shore worker shouted “die, die” as his mother was engulfed in flames.
Judge Lady Stacey deferred sentence on Kelly until January 10, next year, in order to obtain background reports. At this hearing she will determine the minimum number of years he must serve in jail.
She told the jurors: “What you have had to listen to has been distressing and sad.”