NORTH ANDOVER — A man who police say robbed the downtown Sovereign Bank last week was arrested in Boston yesterday after a lucky phone call led police right to him.

Eric J. DiDonato, 25, of Dorchester came onto detectives' radar Wednesday after a Boston family called North Andover police over a child custody dispute.

The family said they were having problems with DiDonato and told police he was staying in a North Andover apartment with friends. They gave an address.

The apartment was near the downtown Sovereign branch, in the area where witnesses last saw the fleeing bank robber. Detectives had even interviewed people in that specific building as they canvassed the area on the day of the robbery.

At the same time, police were receiving tips from residents who had seen someone who fit the bank robber's description walking in the area a week or so before the robbery. The tipsters did not know who he was and hadn't seen him before or since.

Detectives compared DiDonato's driver's license photo to video stills they had of the bank robber.

"He looked very similar to the photographs we had," North Andover police Lt. Paul Gallagher said yesterday. "We put out arrest warrants and a poster this afternoon on (Web site) Mass Most Wanted."

A little more than an hour later, the FBI Bank Robbery Task Force arrested DiDonato in Boston at 1:50 p.m.

"The family had no idea about the bank robbery when they called us. They were just concerned with a custody issue," Gallagher said. "It was a good break for us."

DiDonato is charged with both the downtown bank robbery and shoplifting two LCD televisions from the Main Street CVS a block away.

He was being transported from Boston to North Andover yesterday and will be arraigned this morning in Lawrence District Court on charges of unarmed robbery and two counts of larceny over $250.

Police say DiDonato allegedly walked into the Sovereign branch on Oct. 27 clad in a black scally cap and glasses and passed a note to the teller asking for money. The day before the robbery, DiDonato allegedly walked out of the Main Street CVS with two 15-inch Craig LCD televisions.

Gallagher said police were grateful for the tips from residents that proved helpful in the case.

"People were calling us, telling us they'd seen him a couple times in the area," he said. "They helped it all come together."

Gallagher said DiDonato is known to several police agencies in the state but has never been charged in a bank robbery.