In February, three people were arrested on suspicion of murder or aiding and abetting murder on the lower suspicion level, but they were released shortly afterwards.
In March, another person was arrested on suspicion of aiding and abetting murder, a man aged 18-25.
He was arrested at the time in his absence, but was released shortly after his arrest.
In April, the police made another arrest in the case.
A man aged 20-30 was arrested on suspicion of murder.
However, he too was released.
Several of the people are said to have been known to the police before.
What is the motive behind this murder?
- I do not want to go further into the motif.
What I can say is that the police make the assessment that this is not a randomly selected victim who is the victim of this shooting, but that everything indicates that there is a background to this - why you choose this particular person, says Johan Thalberg, press spokesperson at the police.
In the autumn, the police seized a motorcycle that is suspected to be the getaway vehicle used in the fatal shooting.
The police then searched for information about a man who the same night the murder took place appeared on a surveillance film at Bjurhovda in Västerås.
The police are silent about what the motorcycle and the surveillance film have resulted in.
In the clip above, police spokesman Johan Thalberg tells where they stand in the murder investigation.