Robert R. Lyons, 39, was found guilty on Wednesday of first-degree murder for the stabbing death of his mother after a fight broke out over concert tickets for an Avril Lavigne show.

The incident occurred in the Chicago suburb of Carol Stream on March 14, 2008. Linda Bolek was found lying dead on the floor of the condo she and her boyfriend shared with Lyons. The 61-year-old woman received nine stab wounds in the back and was doused with cleaning solutions and other household chemicals.

Lyons' trial lasted just one week. Prosecutors say a quarrel between mother and son erupted after Lyons became angry that his mother would not phone a friend to arrange tickets for an Avril Lavigne concert that he desperately wanted to see.

Lyons hit his mother over the head with a liquor bottle twice. Then, after stabbing her to death, Lyons allegedly dumped household cleaners, insecticide, and drain cleaner into his mother's body.

The defendant was washing something away, Assistant State's Attorney Amanda Meindl said during closing arguments. He was washing away the problem in his life, his mother.

Prosecutors alleged that Lyons may have been planning to kill Bolek for some time and that the two often had loud, profanity-laced arguments.

While the defense team argued for a lesser second-degree murder charge, Meindl, holding a picture of a smiling Bolek next to one of her face down in a pool of blood and chemicals, told jurors to send a message to Lyons.

She gave you life and you took hers, Meindl said.

The jury of seven men and five women deliberated for about two hours before finding Lyons guilty of first-degree murder. The jurors found his crime particularly brutal and heinous, making him eligible for a life prison term.

According to the Daily Herald, Lyons showed no emotion as the verdict was read.

Outside the courtroom, Linda Bolek's twin sister, Pat Lowry, said she agreed with the jurors' verdict.

She was a good mother, Lowry told the Herald. She did the best she could.

Lowry later told the Chicago Tribune that Lyons began showing signs of mental illness and a volatile temper in his teen years.

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

Robert Lyons will be sentenced in November.