JOIN USThe FBI contacted Sweden after the explosions Saturday, and the offer was accepted, police said Monday.
The FBI team included "specialists in tracing explosives, with extensive knowledge about the methods used by terrorists in bomb attacks in other parts of the world".
The only fatality in the attack was the suicide bomber. Two people were injured. Swedish police had no prior knowledge of the bomber, and part of the investigation includes interviewing people who knew him.
They were also cooperating with authorities in Britain where the man had also lived and studied. His home in Luton, north of London, has been searched by British police. British and Swedish media reported that the suspected attacker was an Iraqi-born Swede, aged 29.
Police earlier Monday confirmed that a threatening email sent just minutes before the blasts was sent by the suicide bomber.