Only the post-911 anthrax mailings has had a higher priority to U.S. Postal Service investigators than June's slaying of postal carrier Clayton J. Smith in the Crafton Ingram Shopping Center.

All 35 Pittsburgh postal inspectors were involved as well as those from West Virginia, Ohio and Kentucky. Over the past nine months, they've conducted some 1,800 interviews and logged 18,000 hours.

But the key piece in the puzzle may have been a remark made by a suspect in an unrelated case two weeks ago, an off-topic, revenge-laced comment that an Ingram police officer chose not to ignore.

None of this comes as a surprise to either postal investigators or those in Ingram as they point to the cooperation that they say led them to identify the shooter as being the woman's 10-year-old son.

At the heart of that cooperation was the work of Ingram Officer Michael Ranalli, who Ingram police Chief Jack Doherty said drew the connection between the woman's comment about her stolen gun and the Smith shooting.

On March 18, Latoya Burnette was supposed to have had a hearing before District Magistrate Dennis Joyce to answer charges of aggravated assault filed by her live-in boyfriend, Lawrence McGirt. McGirt accused Burnette of slashing his face with a razor.

The hearing never took place because McGirt failed to appear. But Burnette at the time would tell Ranalli that she was thinking about filing countercharges against McGirt. Why? Because, she related to Ranalli, McGirt had stolen her gun, a Bryco .380-caliber pistol.

Bryco, Ranalli recalled, was one of two makes of gun that had been identified as likely to have been used to kill Smith, 45, of Collier, W.Va. The mailman was shot while standing by his van in the midday shade.

Another fact that rang with significance was a matter of geography; the officer took note that Burnette lived in an apartment on Ingram Avenue, not far from where the shooting had occurred.

Ranalli immediately contacted Doherty, who, according to the federal affidavit filed in the case, then notified postal inspectors.

From there, the pieces began to fall into place. Investigators said they found the gun box, unspent rounds and an extra magazine clip in a bedroom safe when they searched Burnette's apartment.

They also conducted more interviews and eventually learned that Burnette's son, who was then 9, may have fired his mother's gun.

Neither Doherty nor U.S. Postal Inspector Andrew Richards is surprised that a local police officer played such a key role in helping to resolve the case.

Richards had high praise for the level of professionalism that the Ingram police displayed in assisting postal inspectors throughout the investigation.

"They were absolutely marvelous, nothing but top-of-the-line law enforcement," Richards said.

In defining the importance of the case to the Postal Service, he added, "There is no higher priority than when someone dies as a result of their employment with us."

"It's always good to clear it and we were very glad to have had a hand it," Doherty said.

Doherty said kids often talked to police and that he and his officers frequently used those opportunities to ask them if they knew anything about the shooting, reminding them to contact the police if they ever heard anything about it.

Fliers that were posted throughout the Crafton Ingram Shopping Center offered a $100,000 reward and urged people to contact the police if they had any information.

The fliers stated that investigators believed that either a Bryco or Lorison brand name gun was used.

Richards could not say whether anyone will receive the reward in the case, which he said was nearly concluded.

Burnette was arrested Saturday in North Carolina by federal authorities on a charge of illegally possessing the gun.

Investigators are trying to determine whether the boy could see Smith when he allegedly fired at a tree from the family apartment's second-floor window.

According to the affidavit, inspectors interviewed Burnette's downstairs neighbor on March 19, and she told them that the boy confessed to the shooting in her presence.

It will now be up to U.S. Attorney Mary Beth Buchanan and District Attorney Stephen A. Zappala Jr. to determine the appropriateness of the charges and decide how to proceed.

It's uncertain whether the boy will be charged.

His mother, meanwhile, could face criminal charges of reckless endangerment and endangering the welfare of a minor.