There have been two murders in the past week. A 74-year-old man was driving along a remote stretch of Interstate 55 in northern Mississippi when he was shot and killed on Tuesday.
Three days later, about 50 miles away, a woman was found dead along another highway.
According to investigators, the suspect may be using fake police equipment to pull over victims. Another scenario is the suspect may be pretending to need help on the side of the highyway.
Authorities say there is no connection between the victims. Detectives are looking for a gold, unmarked Crown Victoria that may be using flashing lights.
ABC News contributed to this report.