A man who was killed during an alleged road rage attack made several calls to 911 as he was chased across two states, according to police.
Timothy Davison, 28, was driving home along Interstate 81 in Pennsylvania when he was shot multiple times and later died in hospital.
Pennsylvania State Police said there was no indication the victim had provoked his attacker.
Captain Steven Junkin said Mr Davison may have first encountered the gunman on Interstate 70 in Maryland and travelled up to 15 miles while being pursued before he was forced off the road in Pennsylvania.
He said the victim called 911 in both Maryland and Pennsylvania. Authorities have not released the content of those calls.
Captain Junkin said: "We obviously have an individual out there who was so incensed that he continued to pursue Mr Davison and took it to that next step.
"This actor had murderous intent. He murdered an individual for whatever slight he perceived."
Mr Davison was on his way home on January 4 to Poland, Maine, when he was killed. His funeral took place on Saturday.
Police and the FBI are appealing for help from the public and car body work firms to find a "dark coloured" Ford Ranger XLT pickup with damage on the driver's side caused by ramming Mr Davison's car.
