Schmidt posted them on his Web site in September.
Flynt told Fox News he has seen photos of Frey in person and believes they are authentic.
The bodies were found near where Peterson said he had been Dec.
Schmidt's Arizona-based public relations and production company, which carries his name, also is named in the lawsuit, which alleges misappropriation of Frey's name and likeness, unlawful or misleading advertising, invasion of privacy, and negligent and intentional infliction of emotional distress.
Frey is expected to be one of the key witnesses in the trial of Peterson, accused of killing his 8-months pregnant wife Laci.