A 33-year-old postal worker was in his mail van when he was fatally shot in a "targeted attack," according to Ohio police.
Jonte Davis was shot Saturday afternoon by a gunman who fired from another car, said police in Warren, about 60 miles southeast of Cleveland.
Police said they believe Davis and the suspect knew each other.
Later on Saturday, the suspect's car was discovered in a driveway, and police said they obtained a search warrant for the home and car.
Several people were interviewed, but no one is in custody, police said.
The U.S. Postal Service and the FBI are helping with the investigation.
"Our thoughts and prayers are with Mr. Davis's family, friends, and fellow postal employees, who knew and worked with him," Michael Martel, a spokesperson for the Postal Inspection Service, said in a statement. "Mr. Davis worked for USPS less than a year and was described as a good employee by his supervisors."
The Postal Inspection Service is offering a reward up to $250,000 and asks anyone with information to call them at 877-876-2455.