To New Castle police Chief Thomas Sansone, whoever is setting fire after fire in vacant buildings throughout his Lawrence County city is a yellow-belly and a sneak.

"It's an act of cowardice," Chief Sansone said last week, "because they do it most of the time under cloak of darkness, and most of the time, before you realize what's going on, they're long gone."

That, he said, is one of the things that has made the cases so tough to solve. Despite months of investigation and beefed-up patrols, authorities have not made any arrests.

Another suspicious fire was reported early yesterday. A Lawrence County dispatcher said it broke out at 4:43 a.m. at 826 Morton St., an abandoned house that was the site of another suspicious fire on Aug. 12.

It was brought under control quickly and firefighters cleared the scene within a half-hour.

Before those fires, the most recent one was Aug. 7, fire Chief Thomas A. Maciarello said.

There are other wrinkles that might be contributing to the slow burn of the investigation. The reward for information has been relatively paltry; it stands at $3,000, though it is expected to grow. Most evidence is incinerated at the scene. And investigators believe they are likely dealing with more than one group of arsonists.

"I think we have copycats. I think we have people who may decide it's time to get rid of a certain residence for whatever reason. We haven't ruled any of that out yet," Chief Sansone said.

"There could be a group of individuals, two to three, that may be going around doing the bulk of them. That's a good possibility."

The 36-member police force, in a financially strapped city with limited resources, has handled the bulk of the investigation, relying on state police only for technical assistance.

Absent until lately was the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.

"I don't know that just a few random house fires is going to interest them in coming in. They're busy, too," Chief Sansone said. "As the number climbs over the last year-and-a-half, two years, it gets to the point where you decide you have a problem."

Chief Sansone said the crime data he compiles for state police and the FBI show a decline in arsons for the past two years despite the opposite perception fueled by media coverage. He did not have the numbers readily available.

That said, Chief Sansone finally reached the point of wanting to involve ATF, the nation's recognized experts in fire investigation.

"For the most part, arsons are difficult to solve, mainly because of the [nature of the] scene. When you have experienced people doing it, they're looking at the right kind of clues," said Michael Bouchard, a retired ATF agent and former assistant director at the agency's headquarters.

"The local police and fire, they're like the emergency room. They've got to deal with everything," Mr. Bouchard said. "ATF has the time to pick and choose and be a little more focused on certain types of things that happen."

Chief Sansone said he was about to contact the ATF when an agent who had been tracking the city's troubles called him a few weeks ago.

Russ May, assistant special agent in charge of the ATF's Philadelphia field office, confirmed that the agency has met with New Castle police. He declined to reveal anything else.

"They are looking to help us, and they are helping us right now, but we're hoping to get some more help from them down the road," Chief Sansone said. "They're looking to supplement us with anything we need including some manpower for surveillance or anything we need to have."

Most of the arsons have happened in a New Castle neighborhood called the Lower East Side, where, at last count, there were 109 unoccupied structures.

"If you're a crackhead, firehead, that's perfect for you," Chief Maciarello said.

He was happy to report that the city just got a $150,000 state grant for demolition. A plan is being formulated to eliminate the blight.

Chief Maciarello said there have been 46 confirmed arsons and eight undetermined fires in connection with the spree. Ninety percent have ignited in the middle of the night. Nov. 8 marked a low point, when five fires broke out within 45 minutes of one another in a five-block area.

Investigators found traces of accelerant at a number of fire scenes.

"There was some type of an accelerant, but we never pinpointed what was used, whether it was kerosene, gasoline. In one structure we did find papers, just regular newspapers, that was the cause, stuffed in air ducts and stuff like that."

Chief Maciarello's statistics are not on the most solid footing. He marks the date of the first arson as Jan. 2, 2008, because that is the day he was promoted to chief.

A computer crash in summer 2007 wiped out the department's data, and the chief said he had not combed through records for the second half of that year to see whether there were any arsons then. So anyone trying to establish a firm starting point is out of luck.

Chief Sansone said he does not necessarily agree with Chief Maciarello's assessment of how many arsons occurred and when they began.

"It wasn't a matter that a year-and-a-half ago we started with No. 1," he said. "I don't think there is a defined beginning point."

Mr. Bouchard, the former ATF official, said despite the slow nature of arson investigations, it is important to remain meticulous in collecting information to bolster a case when someone is finally arrested.

Authorities are always looking for a break, he said. And that is true in this case.

"I'm hoping sooner or later we get the break we need," Chief Sansone said.

It might have happened already. Last Monday, just before 3:30 a.m., a Lower East Side resident called police to report the sound of breaking glass next door in a vacant house.

Officers found Rachelle Lombardo, 24, of New Castle, hiding in the basement with two male juveniles. Every window in the house had been broken from the inside out, the woodwork was destroyed, and the door was smashed.

At the police station, Ms. Lombardo and the youths "were talking about when Rachelle started a fire when she was younger. At this time, Rachelle stated that juvenile M.B. told her he started a fire at a blue duplex on Spruce Street several months ago," according to a police affidavit.

Officers found a full gas can inside another vacant house nearby, purportedly for a stolen dirt bike.

Police charged Ms. Lombardo with burglary, conspiracy, criminal mischief and corruption of minors. They are looking into whether the trio might be responsible for any of the arsons.

"We have at least some information to believe they were involved in at least some prior arsons, and it's something we're not ruling out right now," Chief Sansone said.