A psychologist testifying in the dangerous offender hearing of Gary Edwin Mattson said Tuesday Mattson has an anti-social personality disorder and scored high on a test used to classify psychopathic behaviour.
Mattson is facing a dangerous offender designation that would see him imprisoned almost indefinitely after pleading guilty to aggravated assault on St. Albert resident and Edmonton bus driver Tom Bregg.
Dr. Sheila Mary Greer, a psychologist with Alberta Hospital who interviewed Mattson this summer as part of a court-ordered assessment, said after interviewing him and doing a number of tests, she determined he had the personality disorder.
Greer did interviews with Mattson over a weeklong period prior to the dangerous offender hearing.
On a test used to measure psychopathic behaviour, Mattson scored a 28 out of 40. To be deemed a psychopath the person generally has to display a score above 30, but Greer said the score was still very high.
"This places him in what is considered to be the high range."
She said some of that score is reflective of his personality while other parts of it reflect a person's background and personal history.
She said a person's score can fluctuate over time but it is not easy to move up and down.
"Some things will never change, but other things may change, but they will likely change very slowly."
Mattson's criminal record has already been introduced as an exhibit and it includes a lengthy string of offences dating back to his youth, including previous assault convictions and an arson charge. The Crown introduced Mattson's youth record as evidence for the judge to consider when determining whether or not Mattson meets the criteria for dangerous offender status.
Greer also spoke about Mattson's childhood and his struggle with alcoholism and drug abuse. She said Mattson told her he started drinking at 12 and spent much of his teenage years living on the street.
Humiliation triggered attack
Mattson boarded Bregg's bus on Dec. 3, 2009. He failed to pay the fare and after arguing with Bregg for a few minutes, Bregg stopped the bus and told Mattson to get off.
Bregg had initially pulled away after another passenger paid for Mattson, but Mattson continued yelling at the driver.
When Mattson was ordered off the bus he exploded into a rage and viciously attacked Bregg, punching him repeatedly in the face before dragging him out of his chair and repeatedly stomping on Bregg's face.
Greer testified Mattson had a weak memory of the hours before the attack on Bregg and had been drinking considerably since 10 p.m. the prior evening.
She said he told her during the assessment that when he saw the security video of what he had done, he was stunned.
"He said he couldn't believe what he did," she said. "He didn't understand how he did what he did."
When asked about why he attacked Bregg, Mattson said he felt the driver had accused him of being drunk and had made a comment about having money to drink but no money to pay the bus fare.
"It seemed to be his feeling of humiliation in being talked to the way he thought the driver had done."
The hearing continues the rest of this week and is expected to continue into March.
