Investigators say they have solved the mystery of why a holiday traveler was shot to death in the middle of the night on a Pennsylvania highway nearly two years ago: The gunman was targeting someone else driving a similar SUV.

John Wayne Strawser Jr., 38, of Terra Alta, West Virginia, is in jail in his home state, where he faces a separate murder charge in the slaying of a woman earlier this year.

Authorities don't think Strawser knew the victim of the highway shooting, 28-year-old Timothy Davison.

There is strong evidence Strawser was stalking a couple on the night Davison was shot along Interstate 81 and that it is "fair to conclude that at least the initial attack by Strawser was specifically intended for someone else," Franklin County District Attorney Matthew Fogal said.

Davison was driving home to Poland, Maine, in the predawn darkness of Jan. 4, 2014, after visiting relatives in Florida when the driver of a pickup truck started firing at him as the two vehicles crossed from Maryland into Pennsylvania.

The truck rammed Davison's SUV, forcing it onto the snow-covered median. The driver circled back minutes later, as Davison was talking on the phone to a state police dispatcher, and shot him several times in the head, leg and foot before fleeing in the southbound lanes, Trooper Jason Cashara wrote in an affidavit. Davison died shortly afterward at York Hospital.

Authorities initially thought it was a case of road rage.

A major break in the investigation came from Jamie and Courtney Breese, a couple who described themselves as former friends of Strawser. They came forward in April after Strawser was charged with the West Virginia killing.

Before that, "they didn't think he was capable of doing this," Lt. Jonathan Mays, head of the criminal section at the Harrisburg state police barracks, said Monday.

The Breeses said they were traveling north on I-81 at around the same time and vicinity that Davison was killed and that Strawser had been threatening them in cellphone calls and text messages. The couple discussed the possibility that Strawser was looking for them and mistook Davison's silver Mitsubishi Montero for their silver Honda Pilot, Cashara wrote.

A shell casing from the scene matched a casing from Strawser's .44-caliber lever-action pistol and his pickup truck had been painted a different color since the killing, Cashara said.

Law-enforcement officials in Pennsylvania and West Virginia said Tuesday they did not know whether or not Strawser had a lawyer.

Davison's mother said she was relieved that a suspect was in custody.

"Obviously, there's a sense of relief that they got the guy and he's not going to hurt anyone else, but sadness at why are we even going through this," Theresa Allocca, Davison's mother, told the Portland Press Herald. "There's also a little bit of anger and frustration that no one came forward until another person had to die."

Strawser will likely be tried first for the West Virginia killing, Mays said.

"We have to take a back seat to their investigation," he said.