Police launched a murder investigation after the boy, Mahmoud, was found late on Monday in the water at the lake Ösbyträsk on Värmdö island, east of Stockholm.
No foul play was immediately suspected, but a murder probe is standard procedure in Sweden when no cause of death can immediately be established. This is because it allows officers to use more resources to investigate the case.
On Friday the police wrote in a statement that the forensic pathologist's preliminary report found the boy “died in a drowning accident”. Police said they would continue the probe pending the final report.
Police and the organization Missing People launched a search for the boy on Monday with a search dog and drone. His body was first discovered with the help of drone footage.
He had last been seen at around 5.30pm on Saturday on his way to the football pitch with his sister. But Swedish media reported that along the way the sister had gone into a store and when she came out he was nowhere to be seen. His family reported him as missing around an hour later.