Mississippi officials: April incident may be linked to murders TUPELO, Mississippi (Reuters) - Authorities in Mississippi are checking an April incident they say may be related to two highway murders this month that have raised alarms about a killer possibly posing as a police officer. The April 2 incident - which involved a woman being pulled over by an unmarked car and did not end violently - is one of hundreds of leads that officials are following in rural northern Mississippi as they investigate the killings. "We have no way of knowing if this has any connection to the shootings," Tate County Sheriff Brad Lance said on Thursday, "but in light of everything that has happened and all the rumors flying around, we're checking into it." CNN, citing unnamed sources, reported on Thursday that authorities have linked the two highway murders by confirming the bullets used is the two cases are a match. "I cannot comment on that," said District Attorney John Champion, whose district includes the counties where one of the highway killings and the third incident occurred. In the third case, an unmarked gold sedan with flashing white lights pulled over a female driver on Interstate 55 around 2 p.m., according to Lance. "It was a white male in a plaid shirt that was untucked, tan pants, wearing sunglasses," Lance said. She immediately knew that to be odd, since it's supposed to be a police officer. The woman refused to roll down her window, opening it just a crack to communicate with the man, whom she has described as being in his mid-40s. He told her she was speeding and asked for a driver's license; she told him it was in her purse in the trunk and declined to retrieve it, Lance said. When the driver asked the man for his ID and why he was not in uniform, he became upset and told her he was off duty. He struck the side of her vehicle with his hand and told her to just go on. Police are investigating whether the incident is connected to the two killings in May. Thomas Schlender, 74, was found dead in his Ford F-150 pickup truck in an interstate median in Panola County around 1:30 a.m. on May 8. Three days later, 48-year-old Lori Anne Carswell was found dead near her Pontiac Grand Am, which was on the shoulder of a highway, around 2:15 a.m. Both victims had been shot, officials have said. Authorities have told motorists to be wary of anyone attempting to pull them over unless they are certain the person is a legitimate law-enforcement officer. Those with doubts should keep driving, with their hazard lights on, and call 911, police say. Editing By Corrie MacLaggan and Mohammad Zargham