Abdirahman Warsame told The Associated Press that FBI agents in the city of Seattle took DNA samples from Mohamed Mohamud, cut off his phone lines and warned him not to speak to the media. He had been at the family's home on Thursday, two days after FBI agents visited.
They told Mohamud his son Omar may have been in one of two stolen U.N. cars that Islamic insurgents detonated in an African Union peacekeeping base last Thursday. The markings on the cars meant they were not subject to the usual security checks and were allowed onto the base. Seventeen Burundian and Ugandan peacekeepers were among the 21 killed in the Sept. 17 attack, Al Shabab, a local Islamic militia, said was in retaliation for a U.S. commando raid on Sept. 14 that killed Al Qaeda operative Saleh Ali Saleh Nabhan in southern Somalia.
Mohamud had been prepared for the visit by the U.S. federal agents following Internet reports that an American had been involved in the bombing and calls from relatives in Somalia, Warsame said.
"Relatives in Somalia told Mohamed that his son was the bomber who detonated one of the cars. He was very disappointed that his son has died in Somalia," said Warsame. "He was in mourning."
Al Shabab, a powerful Islamist group with foreign fighters in its ranks, claimed responsibility for the last week's attack. This week it released a video pledging allegiance to Al Qaeda and showing foreign trainers moving among its fighters.
If proven, the case would be the second instance of an American-Somali suicide bomber in Somalia. Shirwa Ahmed blew himself up in October 2008 in the northern breakaway republic of Somaliland as part of a series of coordinated explosions that killed 21 people.
Ahmed came from Minneapolis, where law enforcement officials are also investigating the disappearance of up to 20 Americans from the Somali community. Two men from the city, Abdifatah Yusuf Isse and Salah Osman Ahmed, have been charged with aiding terrorists.
Islamic insurgents fighting in Somalia's bloody 18-year-old war have been recruiting English-speaking Somalis with a series of videos and recordings on the internet. They are fighting to overthrow the U.N.-backed government, whose forces currently only hold pockets of the capital with the help of some 5,000 African Union peacekeepers.