Watched Who?, a 1974 film. A low key film, not really science fiction or a spy thriller, more of a mystery. American scientist severely injured in a car crash on the border between East and West Germany has been captured by the East Germany military. He has been nursed back to health but is so badly scarred much of his body is replaced with electronics and his face is replaced with a metal mask. That's before the start of the film where the scientist is supposedly released to the Americans but who is he really? They won't let him return to his Neptune project unless he can prove that he is who he says he is.
The lead American interrogator is played by Elliott Gould, the scientist (?) by Joesph Bova and there are flashbacks to the East Germany military interrogations or are they brainwashing lead by Trevor Howard.
It's quite a good film and unusual. In the states it was released on video under the title Robo Man. I can see why but the film is totally different in style to Robocop. It is also known as The Man with the Steel Mask.
The film was directed by Jack Gold.