Uganda's police chief says there is more evidence that two suicide bombers had carried out the bomb attacks that killed 76 people watching the World Cup final on television last week.
Kale Kayihura said Sunday that the heads of two men have been found at the blast sites and that both remained unclaimed and unidentified. He that Interpol and the FBI are helping Ugandan police identify the two suspected bombers.
Ugandan officials had earlier suspected suicide bombers, and investigators had found an unexploded suicide vest in a disco hall in the capital, Kampala.
Al-Shabab, Somalia's most dangerous militant group, claimed responsibility for the attacks.
Ugandan police said at least 20 suspects have been detained and are being questioned in connection with the July 11 blasts.