A ping from the cellphone of a behavioral health worker who randomly killed a Cleveland grandfather and posted video of the execution on Facebook has been detected in Pennsylvania, according to a report.

The clue emerged as police in Ohio urged residents in Pennsylvania, New York, Indiana and Michigan to be on the lookout for Steve Stephens, 37, who may have fled Cleveland after allegedly gunning down Robert Godwin Sr., 74.

Stephens’ cellphone ping was detected about 100 miles east of Cleveland in Erie, Pa., authorities told CNN. Police in the city told The Post they were not investigating the case.

Stephens worked for Beech Brook, a behavioral health agency headquartered in Pepper Pike serving children through mental health services, foster care and adoption, at-risk youth programs and other services.

An arrest warrant was issued for the suspect, who is wanted on a charge of aggravated murder after posting the shaky video of himself confronting the elderly man — a father of nine and grandfather of 14 — holding a plastic bag.

“Found me somebody I’m going to kill,” he says, chillingly, on Easter Sunday. “I’m going to kill this guy right here. He’s an old old dude, too.”

He then asks his victim a “favor” by saying his girlfriend’s name, Joy Lane, whom Godwin said he didn’t know.

“She’s the reason that this is about to happen to you,” Stephens tells Godwin, who then shields his face with the bag before being shot in the head.

The victim’s son, Robert Godwin Jr., told Cleveland.com that he could not bring himself to watch the footage, which remained on Facebook for about three hours before being removed.

“I haven’t watched the video. I haven’t even looked at my cellphone or the news,” Godwin said. “I don’t really want to see it.”

He said his father, a retired foundry worker, collected aluminum cans and often walked with a plastic bag. The son said he believed his dad was looking for cans Sunday when Stephens approached him.

In a separate video posted on Facebook, Stephens claims to have killed more than a dozen other people.

“I shamed myself. I snapped, I snapped. I just snapped, I just killed 13 motherf——, man,” Stephens says on the phone with an unidentified person, Cleveland.com reported. “I’m about to keep killing until they catch me, f— it. I’m telling them to catch me.”

In the video, he also blames his acts on his girlfriend, saying that he woke up Friday and just decided that he had had enough.

“Now I’m just massacring people,” he says with a laugh.

Police have not verified any other shootings or deaths, Police Chief Calvin Williams said.

“There are no more victims that we know are tied to him,” he said.

Nancy Kortemeyer, a Beech Brook spokeswoman, said in a statement: “We were shocked and horrified to learn of this news today. We are hoping that the Cleveland Police will be able to apprehend Mr. Stephens as soon as possible and before anyone else is injured.”

In one of the videos, Stephens can be seen holding up his Beech Brook employee ID badge.

“I’m killing with my Beech Brook badge on too,” he says.

Stephens also mentions his fraternity, Omega Psi Phi, in one of his Facebook posts. The fraternity issued a statement Sunday night.

“On behalf of the Supreme Council and the members of Omega Psi Phi Fraternity, Incorporated, we lift our sincere and heartfelt prayers and condolences of comfort to the families impacted by the recent shooting in Cleveland, Ohio,” it said.

Williams told reporters late Sunday that “everyone is out there looking for Steve,” who was driving a white Ford Fusion bearing the temporary tag of E363630, Cleveland.com reported.

“We want this to end with as much peace as we can bring to this right now, and we want him to turn himself in,” Williams said, adding that local authorities were working with the FBI and regional law enforcement.

With Post wires