TMZ.com said the tip came from Shane Modica, ex-husband of Bombshell McGee. She happens to be the girlfriend of Bullock's estranged husband, Jesse James.
The FBI would not comment on any investigation, TMZ said. But the Web site said it has heard from sources that Modica said a Missouri man had called him to say McGee wanted to have both her ex- and Bullock killed.
The man in Missouri also reportedly called the FBI there. Agents talked to the local sheriff's office who said the man had suffered a head injury which has led him to "lose sense of reality."
Sources told TMZ the threat was passed along to the FBI in Los Angeles but all investigators have concluded there is no real hit planned.