CLEVELAND — In a rambling video, Steve Stephens said, “I snapped, I just snapped.” But as the manhunt dragged on Monday for the man accused of posting Facebook footage of himself killing a Cleveland retiree, police were unable to explain what set him off.

“Only Steve knows that,” Cleveland Police Chief Calvin Williams said as authorities posted a $50,000 reward for Stephens’ capture in the shooting of Robert Godwin Sr., a 74-year-old former foundry worker.

In the video, Stephens blamed a former girlfriend he had lived with, saying he woke up last week and “couldn’t take it anymore.” But in a statement Monday, the woman shed little light on what might have gone wrong and said Stephens was good to her and her children.

As for the shooting victim, Godwin appeared to have been selected at random, gunned down while picking up aluminum cans Sunday afternoon after spending Easter with some of his children.

A manhunt that started in Cleveland’s gritty east side expanded rapidly into a nationwide search for Stephens, a 37-year-old job counselor who worked with teens and young adults, police said.

“He could be nearby. He could be far away or anywhere in between,” FBI agent Stephen Anthony said.

Law enforcement officials said his cellphone signal was last detected on Sunday afternoon in Erie, Pennsylvania, about 100 miles (160 kilometers) east of Cleveland.

Police reported getting dozens and dozens of tips, and nine schools in Philadelphia were locked down Monday while authorities investigated possible sightings of Stephens. But they said there was no sign he was actually there.

Some of those who know Stephens described him as pleasant and kind, while some said he had a gambling problem. He filed for bankruptcy two years ago.

“He got along with everybody, so it’s just unbelievable what happened,” said Alexis Lee, a friend who saw Stephens last week.

The police chief said: “We are not going to pinpoint a specific thing and say this is what triggered this, because we don’t know.”

Godwin’s daughter said he was killed while collecting cans in a plastic shopping bag.