ERIE (AP) -- A pizza deliveryman who told police he had been forced to rob a bank was killed by a bomb that was attached to a locked metal collar secured around his neck, an FBI agent said Tuesday.

Hoping to find new leads in the bizarre case, law enforcement officials released photographs of the collar and the lock, believing someone may recognize the device and help them by calling a telephone tip line. FBI agent Bob Rudge and other members of the law enforcement group investigating Brian Douglas Wells' death Thursday refused to provide any details about the bomb itself.

A state police spokesman said investigators are still trying to determine whether Wells was a willing participant in the bank robbery outside Erie last week or if he was a "bomb hostage."

FBI experts in Quantico, Va., are reconstructing the bomb, which hung from the lock over Wells' chest, and analyzing an extensive, multipage note that was used by the robber, Rudge said. One part of the note was for bank employees, demanding cash during the robbery, and the other part was instructions for the robber, officials said.

Wells' death has transfixed northwestern Pennsylvania since last Thursday, when police surrounded the 46-year-old pizza deliveryman following the robbery of a PNC Bank branch. After exiting his car and being handcuffed a short distance from the bank, Wells told authorities he had a bomb strapped to him and that someone -- he apparently did not say who, if he knew -- had started a timer on the bomb and forced him to rob the bank.

While waiting for a bomb squad to arrive, the bomb exploded, killing Wells. No one else was injured.

In the moments before the bomb exploded, Wells asked police why none of them was helping to remove the bomb.

Since Wells' death, law enforcement officials have been chasing down leads but would not discuss if they have had any success. Rudge said Tuesday that authorities hope someone who recognizes the collar and lock will give them information that could allow them to determine whether Wells was coerced into robbing the bank or lead them to anyone else who may have been involved.

The collar was "unique in its construction," including a lock with four keyholes and a three-digit combination dial, Rudge said. Bureau officials who examined the collar and lock do not believe it was commercially manufactured, he said.

Rudge and other officials refused to discuss the specific contents of the note or the makeup of the bomb, including whether it had a timer or a remote control device.

The FBI posted the photos of the locking device on its Web site: www.fbi.gov. Its toll-free telephone tip line can be reached at 1-866-219-2008.

About 50 people -- including FBI personnel, Pennsylvania State Police, and officials with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives -- are involved in the investigation and are "chasing leads on an hourly basis," Rudge said.

He said he knew of no similar incident ever taking place in northwestern Pennsylvania.

Meanwhile, officials released information from an autopsy on one of Wells' co-workers, Robert Pinetti, 43, who was found dead Sunday at his home in nearby Lawrence Park Township. Pinetti had refused medical assistance at about 5 a.m. that day and family members found him unresponsive in his bed a few hours later, police said.

Erie County District Attorney Brad Foulk said Pinetti had a history of substance abuse and preliminary testing appeared to show methadone and "Valium-type" drugs in his system. There was no trauma and authorities said they have nothing connecting his death to Wells' case.