I’m currently watching the documentary The Day Kennedy Died (ably narrated by Kevin Spacey). Buell Frazier was Lee Oswald’s co-worker at the Texas School Book Depository and gave him a ride to work on the morning Kennedy was assassinated. He is one of the people interviewed for the documentary. At one point, Frazier says that chief interrogator Captain Will Fritz interrogated him angrily and even presented him with a typed statement implicating himself as an accomplice in the assassination. Of course, he refused, and after threatening him again Fritz left the room and that was the last Frazier saw of him.
Buell Frazier has frequently been interviewed on the subject and has never been considered as a suspect since that point. This seems to make Fritz’s confidence that he had the right man (in Oswald) quite a bit less credible, even for people who believe that Oswald was the lone gunman.