Pettersson grew up in a middle-class family in Solna outside of Stockholm and later moved to the suburb Sollentuna. In his youth he attended a theatrical school where he was considered promising by at least one of his teachers. However, Pettersson suffered a head injury that he would never fully recover from. Subsequent to his injury, Petterson began a period of substance abuse which would eventually force him to drop out of school. In 1970, he stabbed a man to death in central Stockholm, during a street brawl, in what the Swedish press dubbed the "bayonet murder". The killing took place just around the corner from what would later be the site of the Palme assassination. Pettersson was sentenced to closed psychiatric care for manslaughter for the killing. After less than two years he was released and continued a life of petty crime, which financed his alcohol and drug abuse.
On the night of 28 February 1986, the Swedish Social DemocraticPrime Minister Olof Palme was shot and killed in Stockholm as he walked home from a cinema with his wife, Lisbet Palme. The killer quickly escaped, leaving no traces except two.357-caliber Magnum bullets. Witness statements about his appearance were confused and contradictory. In 1988, Pettersson was detained and accused of Palme's murder, after an investigation that appeared to have started based on rumors about his involvement among fellow small-time criminals and drug addicts. The initial investigation had uncovered little of signficance, but, once detained, Pettersson was picked out from a ten-person police lineup by Lisbet Palme. Pettersson denied any involvement, claiming he had liked Olof Palme and had left central Stockholm at the time of the murder. However, Lisbet Palme's identification in combination with statements by acquaintances of Pettersson, who stated that he had been near the scene of the crime at the night of the murder, led to a 1989 conviction for murder. Pettersson was sentenced to life imprisonment. Just a few months later, however, Pettersson was freed on appeal. The court cited a lack of evidence, including the missing murder weapon, and raised questions over the reliability of Lisbet Palme's identification. Pettersson was awarded about $50,000 in compensation. Although Pettersson appears to have quickly spent the money on alcohol and drugs, he remained in the media potlight and would subsequently augment his income by selling TV and newspaper interviews. In several interviews, particularly on TV3, Pettersson was encouraged to admit to killing Olof Palme. In such situations, he repeatedly engaged in what-if scenarios that came close to an admission of guilt. However, his confession was not treated seriously, and, when cornered, he argued that he had simply seeking money for yet another television appearance. Police investigators continued to investigate Pettersson, with many reportedly feeling that he had got off on a technicality and was in fact guilty. In 1998, the Supreme Court rejected a prosecutor's appeal to retry Pettersson, citing that the new evidence put before them was "not of such nature that a new trial can be granted in the case."
Coma and death
After a brawl with police, Pettersson was admitted to hospital on 15 September 2004. On leaving hospital the following day, he reportedly fell and suffered a cerebral haemorrhage, going into a coma. Pettersson died at Karolinska University Hospital on 29 September 2004. Pettersson was buried in Sollentuna in January 2005.
