OSLO, Norway – Anders Behring Breivik knew it would take practice to be able to slaughter dozens of people before being shot by police. In a chilling account, the far-right fanatic claimed Thursday that he sharpened his aim by playing the video game “Call of Duty: Modern Warfare” for hours.

Breivik told an Oslo court he also took steroids to build physical strength and meditated to “de-emotionalize” himself before the bombing and shooting rampage that left 77 people dead. He figured he had no more than a 5 percent chance of not being killed by police.

His lack of remorse and matter-of-fact description of weapons and tactics — he even considered using a flame thrower — were deeply disturbing to families of the victims, most of whom were teenagers.

Breivik testified that he prepared for his attacks by cutting off contact with the outside world and devoting himself to video games. He said he played “World of Warcraft” for 16 hours a day while living with his mother in 2006 and, starting in January 2010, played “Call of Duty: Modern Warfare” to get a feel for how to use rifle sights.

Christopher Ferguson, a clinical psychologist at Texas A&M International University, said that although some research suggests action games can improve “visuospatial cognition,” it’s difficult to say whether Breivik could have improved his accuracy by playing “Modern Warfare.”

“Let us keep in mind too that he was shooting kids on an island from which they could not escape easily,” Ferguson said. “That does not require great accuracy.”

And while the belief persists of a link between violent video games and violent behavior, studies have shown that is not the case, he said.

Norway has been roiled by the trial since it began Monday. The public TV network NRK is broadcasting live from court but isn’t allowed to show Breivik’s testimony.

Pictures of the confessed mass killer, smirking or flashing his clenched-fist salute, have filled newspaper front pages. For readers who’ve had enough of his antics, the Dagbladet newspaper website has posted a link to a Breivik-free edition.

But many say finding out what motivated Breivik is crucial for the country to put the July 22 massacre behind it.

“We should consider ourselves lucky to have this trial to uncover his thoughts and values,” said Oeystein Stoltenberg, a 59-year-old Oslo resident.

Breivik, who styles himself as a modern-day crusader, has confessed to the attacks but rejects criminal guilt, saying he was acting to protect Norway and Europe by targeting a left-leaning political party that he claims betrayed the country by opening it up to “Islamic colonization.”