According to the Associated Press, an FBI investigation concluded that a government scientist, Dr. Bruce Ivins, acted alone, but that conclusion was questioned by some of his colleagues, who doubted he could have created the weapons-grade anthrax that was used. Prior to the FBI report implicating Dr. Ivins, another scientist, Steven Hatfill, was investigated. After his name was cleared, he successfully sued the government for invasion of privacy and received a $5.8 million settlement.