F'N SICKO: Son, 39, stabbed his mother to death and doused her in chemicals after she refused to buy tickets to an Avril Lavigne concert

Guilty: A Chicago jury found Robert Lyons guilty of stabbing his 61-year-old mother to death and pouring drain cleaner over her body in the condo they shared with her boyfriend

A son stabbed his mother to death and poured chemicals over her body after she refused to buy him tickets to an Avril Lavigne concert, a jury was told.

Robert Lyons, 39, is facing possible life in prison after being found guilty of first degree murder.

Angry that his mother, 61-year-old Linda Bolek, wouldn't call a friend to arrange concert tickets, Lyons stabbed her nine times in the back and then doused her with insecticide and drain cleaner.

Mrs Bolek was found later on March 14, 2008, lying on the floor of the condo she shared with her boyfriend and her son.

'The defendant was washing something away. He was washing away the problem in his life, his mother,' Assistant State's Attorney Amanda Meindl told a DuPage County court in Chicago yesterday.

During the week long trial, prosecutors said mother and son had one or two flare-ups a month. Lyons had planned to kill Mrs Bolek for some time, the jury heard.

Holding up two photographs – one of the victim smiling and an another of her lying face down in a pool of blood and chemicals – Ms Meindl said it was important to send a message to Lyons.

'No one deserved to die the way she did, at the hands of her son,' lead prosecutor Ann Celine O'Hallaren added after the verdict.

'She gave you life and you took hers, and you're guilty of first-degree murder,' she said.

Assistant Public Defender Mark Lyon didn't deny that Lyons killed his mother, but pressed for a lesser charge of second-degree murder.

The jury also found Lyons guilt of wanton cruelty, making him eligible for an extended sentence of up to life behind bars.

Lyons' aunt, Pat Lowry, was in court to hear the conviction. She told the Chicago Tribune that her nephew began showing signs of mental illness and a volatile temperament in his teens, but she added that 'she didn't want to see it.'

'I told her that Robbie needs help. She hung up on me and didn't talk to me for a year,' said Ms Lowry.

Despite that, she said Mrs Bolek 'was a good mother. She did the best she could.'

Sentencing is on November 22.