The suspect, who was 17 at the time, has since April been in custody in connection with another case. He is suspected of kidnapping and attempted murder after an incident which left an underage boy with gunshot wounds in Skärholmen in December 2023.
Another two teens are in custody on suspicion of protecting a criminal and a third boy is suspected of aggravated weapons offences.
A further two people are suspected of involvement but are not in custody.
The 18-year-old denies the murder allegations.
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