In both cases, victims were fatally shot and their vehicles left on the side of the road, The DeSoto Times-Tribune in Hernando, Miss., reported Tuesday.
"We feel like both incidents were definitely tied together," District Attorney John Champion said Monday. "Both were on the side of the road and were shot."
The prosecutor did not confirm reports that the two victims were pulled over by someone posing as a law enforcement officer using blue flashing police lights on an unmarked car.
Champion said motorists have a right to drive slowly to "a place of safety" with their flashers turned on if they're pulled over by a vehicle with flashing blue lights, presumably a law enforcement officer.
"You have the right to turn on flashing lights and pull to a lighted, safe area," Champion said. "It doesn't give you carte blanche right not to stop at all."
Shell casings that could possibly be from the weapon indicate the two shootings may be related, sources knowledgeable about the investigation said.
Warren Strain, Mississippi Highway Patrol spokesman, said Monday authorities are investigating similarities between the two incidents which occurred last week.
"There are some similarities between the two incidents, mainly the fact they happened alongside a Mississippi highway," Lt. Col. Larry Waggoner, Mississippi Bureau of Investigations Director, said. "The concern is that someone is posing as a law enforcement officer and that is how these vehicles end up on the side of the road."