Updated

A Swede charged with three counts of murder and 12 counts of attempted murder in a string of shootings that spread fear among immigrants in the city of Malmo pleaded not guilty as his trial started Monday.

Peter Mangs, 40, a social dropout with a psychiatric history, listened quietly as the charges were read in the packed courtroom.

Mangs was arrested in November 2010 following a manhunt for a gunman police had linked to more than a dozen shootings in 2009-2010. Investigators later linked him to two 2003 murders.

Chief prosecutor Solveig Wollstad presented evidence found in Mangs' apartment, which included a gun equipped with a silencer, ski masks, wigs, ammunition, and gun parts.

Wollstad claimed Mangs had used a Glock in the shootings but changed the barrels in an apparent attempt to make it harder for ballistics experts to trace bullets to the gun.

Victims, nearly all of whom had some type of immigrant background, were shot through windows of apartments, businesses, parked cars, or as they were walking along the street. Several were shot through bags that Mangs had fitted with holes — the likes of which police later found in his apartment.

Tellingly, the keys to the apartment of 66-year-old Iranian-born Kooros Effatian, who was shot dead on his sofa in 2003, were also found in Mangs' flat.

Mangs received a gun license in 2002 and eventually became a member of a shooting club in Sweden, prosecutor Hakan Larsson said. He bought two guns — a Glock and a Unique — in San Diego, California, had them shipped to Boca Raton, Florida, where he picked them up in 2003 to smuggle them to Sweden.

Prosecutors showed the court how combat clothes, including a multi-pocket vest with a large knife on the back, could be worn under jackets. Such a vest was similar to those that Mangs used, prosecutors claimed.

Larson described Mangs as someone who struggled to get a job, lived off welfare and was often in contact with psychiatrists.

"He had tried to go back to his job but didn't want to because he didn't get sufficient intellectual stimulus," Larsson said.

The prosecutor also said the suspect once told doctors he had seen a film about psychopaths and cannibalism and thought it was a good portrayal of himself.

In 2009, Mangs was diagnosed with Asperger's syndrome. A sufferer usually exhibits normal to high intelligence but has difficulties in socializing and communicating, Larsson said.

Mangs' lawyer said the prosecutors' case was weak. "There is no DNA, no fingerprints, no telephone data that can put him in these places," Douglas Norking said. "The prosecutor cannot provide any motive either."

The shootings spread fear in Malmo — Sweden's third largest city and one of its most ethnically diverse. Forty percent of the city's 300,000 residents are first- or second-generation immigrants.

Swedish media have drawn parallels to a racist gunman who hunted down immigrants in Stockholm in the 1990s. After evading capture for nearly a year, John Ausonius was convicted of one murder and nine attempted murders and is now serving a life sentence.

Comparisons have also been made between the Malmo shootings and the killing of 77 people in Norway last July by Anders Behring Breivik.