FBI spokeswoman Laura Eimilller confirmed the U.S. agency contacted Thai authorities after agency officials met Friday with the "Kung Fu" actor's half-brother, Keith, People.com reported Saturday.
Thai authorities have yet to respond to the FBI's offer, Eimiller said.
Mark Geragos, an attorney for Keith Carradine, said his client wants authorities to thoroughly investigate his half-brother's death at a Bangkok hotel.
Carradine's body was found hanged in a hotel suite Wednesday by a maid. Thai police said ropes had been tied around the "Kill Bill" actor's throat and genitals.
Geragos told People magazine the details surrounding the actor's death have left his friends and family unable to fully grieve.
"It's hard to start the grieving process when you don't have all the information on what happened," Geragos said. "Family members, including Keith and Hayley (DuMond, Keith's companion), are frustrated and in shock."