Some residents slept with baseball bats near their beds, others looked over their shoulders when they ventured outside as police widened their search to neighbouring cities and states for a Cleveland man who shot an elderly man and posted the killing on Facebook.

In a news conference broadcast live on the city's TV stations on Monday (April 17), Cleveland police and other law enforcement officials, including the FBI assured nervous residents of this trendy Northeastern Ohio city that they had intensified their search for the suspect, Steve Stephens, widening it nationwide.

A US$50,000 ($70,000) reward was posted for information leading to his arrest.

"Obviously, this individual is armed and dangerous, and quite frankly at this point he could be in a lot of places,"said FBI Special Agent in Charge Stephen Anthony. Cleveland police issued an aggravated murder warrant for the suspect late Sunday.

A heavier police presences was noticeable in Cleveland's downtown area, as people returned to work after the weekend. Some hotels went into lock-down after the shooting, and Cleveland State University were told to shelter in place or avoid the campus, but the advisory was lifted Sunday evening.

The greater Cleveland area that includes Akron and Canton has a population of around 2 million was the site of the Republican National Convention in July last year where the party nominated Donald Trump as their successful presidential candidate. A greater security presence was expected at today's Cleveland Cavaliers playoff game against the Indiana Pacers.

Meanwhile, police and the FBI widened the search to include the neighbouring states of Pennsylvania, Indiana, Michigan and New York. Stephens face was plastered on billboards and alerts and information about him posted on illuminated signs on interstates.

A report that he had been spotted as far away as Philadelphia, Pennsylvania, an eight-hour drive from Cleveland, proved false, but resulted in 30 schools in the area on lockdown.

Stephens, 37, is accused of shooting 74-year-old Robert Godwin as he was simply walking home from having anEaster meal with one of his sons and a daughter-in-law on a unusually warm spring Sunday afternoon when he was shot point blank in cold blood.

In a disturbing video that was not streamed live as earlier reported but posted later on Facebook, and has since been taken down, an unseen man pulls up in his Ford Fusion on a quiet street not far from Cleveland's sprawling Cleveland Clinic complex, Rock and Roll Hall of Fame, and vibrant arts district.

Godwin is seen shuffling down the street carrying a plastic bag in which he is collecting aluminium cans, as a man in the video mutters: "I found somebody I'm about to kill.""I'm about to kill this guy right here; he's an old dude."

The man then gets out of his car, walks up to Godwin and asks him to say the name of "Joy Lane", reportedly a woman that Stephens was acquainted with.

A puzzled Godwin eventually raises his hands in front of his face when a gun is pointed at him and the shooter says: "She's the reason why this is about to happen to you."

A gunshot is heard, Godwin recoils and the video next shows him on the ground, blood streaming from a head wound.

Facebook said late Sunday that the video was online for about three hours before it was removed and that Stephens' profile had been deactivated.

A son said Godwin was a retired foundry worker and the father of ten children and grandfather of 14,

The son, Robert Godwin Jr, told the Cleveland Plain Dealer: "I haven't watched the video. I haven't even looked at my cellphone or the news," Godwin Jr. told the newspaper. "I don't really want to see it."

In TV interviews, friends and relatives wept and described the elderly Godwin as a good man who always had a kindly word for everyone. They also warned people about donating to several GoFundMe accounts online as they had not been set up by Godwin's family.

Police said Stephens has no prior criminal record except for numerous traffic violations. Ironically, he had worked since 2008 as a vocational specialist and youth mentor at a behavioural health agency in a Cleveland suburb called Beech Brook, which closed its offices were closed yesterday out of caution, and said it was "horrified" by the shooting.

Cleveland police chief Calvin Williams told the city's residents "not to panic".

"We're asking the public to remain vigilant. We're asking you to go about your day, but be careful."

Williams also said Stephens had spoken with police on his mobile phone after the murder, but that they had not had contact him since. He would not comment when reporters asked about a report that a mobile phone ping had placed Stephens in Erie, Pennsylvania

"We're still asking Steve to turn himself in," said Williams. "But if he doesn't, we'll find him."

One of the murdered man's daughters, Tonya Godwin-Baines, told WJW TV that the family is devastated, but had compassionate words for his killer.

"To the young man who murdered my daddy, I ask that you please surrender," she said. " I forgive you, and love you but most importantly, God love you. God can heal your mind and save your soul. Please!"