The suspected crimes are being investigated by the international public prosecution office.
Information about the investigations into the possible war crimes is limited, but Swedish Radio News understands that no one is in custody. According to prosecutor Thomas Ahlstrand, war crimes are difficult to investigate.
It is very complicated and delicate. It's another country, another language and another culture. You can't just travel around Raqqa, knock on doors and ask people if they have seen anything in the car park", he says.
Click on the play button to hear more about the ongoing investigations.