The victim, a 38-year-old man, was found at home by colleagues who went looking for him when he didn’t show up for work on February 26th.
They found the man dead, sitting at his kitchen table holding a mobile phone, the Aftonbladet newspaper reports.
The exact circumstances which led to the killing remain unclear.
The 44-year-old suspected killer had shared a few beers with his neighbour the evening of February 25th.
Investigators believe the 38-year-old victim was drunk lying in his bed when the 44-year-old placed the bolt gun on his forehead and fired.
Bolt pistols are normally used on livestock, firing a projectile or ‘bolt’ at high speed into an animal’s forehead, often damaging the brain in order to render it unconscious prior to slaughter.
According to the indictment, the bolt pistol used in the death of the 38-year-old fired a projectile more than 6 centimetres in length and 12 millimetres wide, into the victim’s skull.
But the man didn’t die instantly from the blow, according to prosecutor Per-Åke Kvarnström.
“We’re talking about a rather long and drawn out death, it may have lasted more than six hours,” he told Aftonbladet.
“The assailant was seen leaving the scene at 7pm on the night of February 25th. At eight o’clock the next morning a colleague called the 38-year-old. Someone answered with a moan, but the person didn’t understand what he said.”
When the 44-year-old was arrested, police found a bolt gun and box of ammunition in his home.
The trial of the 44-year-old, who denies the charges against him, is expected to start on April 23rd.