Salman Abedi, 22, died in the attack at an Ariana Grande concert in northern England. The bombing left 22 dead and more than 60 injured.
Abedi's 23-year-old brother Ismail was arrested in Manchester on Tuesday. A younger brother, 18-year-old Hashim, was also arrested in Tripoli on Tuesday night, a Libyan government spokesperson told the Associated Press. The anti-terror force that arrested him said in a statement, "The brother was aware of all the details of the terrorist attack." He was reportedly in the process of receiving cash transferred from Salman at the time of his arrest.
The bomber's father, Ramadan Abedi (also known as Abu Ismail), was also detained in Tripoli on Wednesday. Before his arrest, he told reporters his son was innocent.
In addition to the brother in Manchester, British police officers said they'd detained four potential associates of Abedi in the U.K. on Wednesday. "It's very clear this is a network we are investigating," Chief Constable Ian Hopkins told the AP.