The Investigation Discovery show, "My Brother the Serial Killer," will be broadcast Wednesday.
The film is a look at Glen Rogers, who was convicted by a Florida jury in 1997 for killing a woman.
Rogers was also convicted of murder in California and is a suspect in homicides in several other states.
Rogers met Nicole Brown Simpson in 1994 when he was living in Southern California, his family says in the documentary.
A criminal profiler in the film says he received paintings by Rogers with clues possibly linking him to the murders of Simpson and her friend.