Federal authorities have figured out how a pizza deliveryman wound up in the middle of a bizarre bank robbery scheme that ended with a bomb around his neck exploding, a law enforcement official told The Associated Press.

Brian Wells, 46, robbed a suburban Erie bank in 2003 with the bomb attached to his neck and then was killed when it exploded as he sat handcuffed in a parking lot while police waited for a bomb squad.

No one was charged as authorities struggled to determine who was behind the plot and whether Wells was an innocent victim or willing participant.

But indictments are expected, likely by next month, said the official, who spoke on condition of anonymity.

At an afternoon news conference, U.S. Attorney Mary Beth Buchanan said, "We now believe we have a much better understanding of what happened on Aug. 28, 2003. This investigation is nearing a close and we hope that it will be concluded in the very near future."

Buchanan would not elaborate or take questions.

"The government knows what happened the day of the incident. We know all the details that led up to the death of Brian Wells and all the parties involved," the official said.

Investigators from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, the FBI and Pennsylvania State Police traveled coast to coast to interview witnesses and chase down leads, the official said.

Buchanan met for about three hours Friday with federal investigators about the evidence compiled so far.

Earlier Friday, Buchanan said she called the meeting because, "In more complicated cases, I like to meet personally with the law enforcement agencies to discuss the case and, in many cases, review the evidence myself."

Wells told police before he died that he had been accosted by gunmen who locked the bomb on his neck and forced him to rob the bank when he went to deliver a pizza to a TV tower on a dead-end road.

Wells' family has said they believe he was just a victim, and have criticized the pace of the investigation.

Wells' brother, John Wells, 44, of Phoenix, said the family won't be happy until justice is meted out.

"The family will be satisfied when everybody is held to account for their actions that day," Wells said. "We want everybody to take responsibility for what they did before and after this happened."

An attorney, Lawrence D'Ambrosio, has said the FBI has repeatedly interviewed his client about Wells' death. D'Ambrosio did not immediately return a message left at his office Friday.

The client, Marjorie Diehl-Armstrong, is serving seven to 20 years in state prison for pleading guilty but mentally ill to killing her boyfriend, James Roden, in 2003.

Roden's killing led police to question Diehl-Armstrong in the Wells case because Roden's body was found in the freezer of a man named William Rothstein, who has since died. Rothstein's house was near the TV tower.

Buchanan said the investigation has been complicated by the deaths of at least two witnesses. She would not say if Rothstein, who died of cancer in July 2004, was one of those witnesses.

Buchanan plans to meet once more with investigators to discuss evidence, witness availability and other logistical details before indictments are sought. The grand jury is not expected to hear the government's presentment — a formal detailing of the evidence — until next month, the law enforcement official said.