REVERE — When Sergeant Charles Callahan stopped in a Revere parking lot Wednesday night to ask if two men needed assistance changing a flat tire, he thought he was lending a friendly hand.

One of those men, he found, was wanted in the brutal killing of a 91-year-old woman in Florida.

That man, Dominic Panzino, 36, appeared in Chelsea District Court Friday after he allegedly confessed to Clearwater, Fla., police that he strangled and beat Kathryn Schroepfor inside her home.

Her body was found on May 26.

In court Friday, Panzino agreed to return to Florida to face the murder charge against him. Before that can happen, however, authorities must decide whether to dismiss charges he faces in probation violations pending against him in Lynn and Malden district courts.

Panzino was ordered held without bail and is due back in Chelsea court Thursday.

“We had a confession for the murder, and it’s a particularly heinous one at that, so we’re very happy with the outcome of this,” said Revere Police Chief Joseph Cafarelli.

Panzino, listed in court documents as a Framingham resident, was arrested around 10:30 p.m. Wednesday by Revere police as he tried to change the tires on a stolen rental car, tires that had been deflated by security spikes at the rental facility, officials said Friday.

As Callahan stopped his cruiser next to the men in the restaurant parking lot and got out to offer assistance, he heard a bulletin on his radio stating a gray Mustang had been stolen from a nearby rental car center.

The suspects heard it, too.

The accomplice ran and Panzino tried to follow but was apprehended, Callahan said.

“He was frantic,” Callahan said at the Revere police station Friday.

“He heard the transmission over the radio — I was standing right next to him — and as soon as he heard, his eyes got wide and he tried to get by me.”

After Panzino was arrested, police quickly realized that he was wanted in Florida, and Clearwater police arrived the next morning to interview him.

The arrest of Panzino brought an end to an apparent string of crimes that began with the killing of Schroepfor. At the time, Panzino was living next door to the woman, at the home of his employer.

According to the Tampa Bay Times, Schroepfer’s front door was unlocked when her body was discovered, which suggests that she may have opened the door for the killer.

Clearwater police have been looking for Panzino since Schroepfor’s body was found.

Authorities in both states alleged he stole the woman’s credit cards and fled in a 2007 Chevrolet Express, the delivery van belonging to his employer, Midwestern Meats. Police suspect him in the sexual assault of a woman in Virginia during his journey north, Cafarelli said.

Revere police said the van was found abandoned in East Boston.

They believe Panzino and his accomplice went to the Thrifty Car Rental center in town and tried to rent a car. When they were denied, they jumped into a car in the lot, and tried to evade the security gate by driving out as another customer was exiting.

But Thrifty’s security system activated, Cafarelli said, and the back wheels of the car were pierced by metal spikes while a gate lowered, damaging the back of the vehicle. Despite the two flat tires, the men drove away and pulled over in the parking lot of Banana Boat restaurant on Beach Street.

While in custody in Revere, Panzino was interviewed by Clearwater detectives for three hours Thursday, during which he confessed to killing Schroepfor, said Revere detective Lieutenant Jon-Richard Goodwin.

Goodwin said that after looking at photos from the crime scene, he counted this killing as one of the most horrific he had ever worked on.

“Eventually, he told the story,” Goodwin said. “People’s consciences get the best of them.”

Panzino has a criminal history in Massachusetts stretching back to at least 1993, according to court documents.

Cafarelli recalled that he arrested Panzino 15 years ago when he was a patrol officer.

One of Panzino’s outstanding warrants was from Malden for violating his probation after being convicted for receiving stolen property and possessing instruments for burglary in 2008.

That same year, Panzino was charged with three counts of aggravated rape, kidnapping, and kidnapping for extortion, but those charges were dismissed after Panzino promised not to contact the victim in that case.