Formerly a price control attorney, Questadt participated in the senate investigations against the Mafia and the Corleone family in 1959, despite having been present at the New Year's Party in Cuba with Michael Corleone. He was associated with Hyman Roth, who was suspected of masterminding the senate hearings against Michael Corleone.
Fredo Corleone's concealing of Questadt's allegiance was part of the reason why he was expelled from the Corleone family.
Behind the scenes
In the original script, Questadt was a member of Senator Geary's party visiting Michael and Roth in Havana, attending the "Superman" show and arguing politics with Geary. In the film he only appears in the Senate hearings.