As the investigation into a string of sniper killings enters a new phase this week, multiple law enforcement agencies have broken away from the regionwide sniper task force and are focusing solely on their own cases, spurring new tension over access to information, law enforcement sources say.

There is frustration, for example, that the results of any questioning of the two suspects, John A. Muhammad, 41, and John L. Malvo, 17, has not been shared with each local jurisdiction involved in the case.

"Everyone is keeping stuff to themselves," one investigator said.

"A couple of agencies have not had the opportunity to interrogate, nor have they been privy to what's going on," said another law enforcement official. "They need a lot more information than they're getting in order to go forward on prosecutions."

As part of their investigation, officials are trying to determine whether Malvo pulled the trigger in one or more of the killings. One law enforcement source said investigators have identified latent fingerprints from both Muhammad and Malvo on the Bushmaster assault rifle.

Some involved in the case believe Malvo may have written, or helped to write, one or both of the notes left at two crime scenes.

"We're trying to determine who did what and who is responsible for what," a law enforcement source said.

Police in Tacoma, Wash., said last night that they considered Muhammad and Malvo suspects in the fatal shooting in February of a woman in Tacoma. Police Chief David Brame said the two had access to a handgun that, according to ballistics tests, fired the shots that killed Keenya Cook.

Cook did not know Muhammad, according to her relatives, but had shared a house with her aunt, Isa Nichols, who helped Muhammad launch an unsuccessful car repair business. The relatives said friction later developed between Muhammad and the aunt.

Brame said authorities were told that Muhammad and Malvo had access to a .45-caliber handgun owned by a Tacoma man. Brame said the Washington State Crime Laboratory identified the gun as the one used to shoot Cook. He said that no charges had been filed but that Tacoma officials intended to pursue the matter.

Brame also said tests showed that shots fired in May at a Tacoma synagogue came from a second handgun to which Muhammad and Malvo had access.

Despite some problems with cooperation before last week's arrests of Muhammad and Malvo, the various jurisdictions shared a common goal: to find the sniper. But now, they are working independently to compile sufficient evidence to prosecute shootings in their own jurisdictions.

D.C. Police Chief Charles H. Ramsey said that while he had about 40 detectives, officials and forensics officers assigned to the task force during the past three weeks, that team is now zeroing in on the one shooting in the District.

He said his detectives are working closely with the U.S. attorney's office to bring charges and build a case against Muhammad and Malvo in the fatal shooting of Pascal Charlot, 72, on Oct. 3.

In Spotsylvania County, authorities are working on building their own case against Muhammad and Malvo. Muhammad was indicted by a county grand jury yesterday on numerous charges, including capital murder. Malvo faces parallel charges in juvenile court, and officials said they would attempt to try him as an adult.

"Now the real work starts," said Spotsylvania Sheriff Ronald T. Knight, "because these cases have to be built."

Knight said yesterday that his investigators are meticulously trying to re-create the two shootings in his county -- of a 43-year-old woman who was wounded Oct. 3 as she loaded her car after shopping and of Kenneth H. Bridges, 53, who was killed Oct. 11 as he pumped gas at an Exxon station in Spotsylvania.

Knight said detectives have been narrowing down where the sniper was when the shots were fired, especially in the Bridges slaying.

One source said that at 4:30 a.m. Oct. 11, Muhammad and Malvo checked into a Ramada Inn on Jefferson Davis Highway, across the street from the Exxon station.

Knight said detectives believe that the suspects might have parked their car in the motel's lot, which would have provided a clear line of sight and a cover of short trees and shrubs. By the time police surrounded the motel, the suspects were long gone.

In Maryland, investigators, armed with a warrant, began yesterday to take apart the blue Chevrolet Caprice in which Muhammad and Malvo were found. One law enforcement source said that when police found the car, a blue plastic flap had been placed over a hole in the trunk so the opening would not be apparent. Some investigators believe that the shooter could have lain prone in the trunk and shot or aimed through the hole.

FBI scientists are comparing fingerprints found on the car, the guns and items taken from the homicide scenes. Analysts are also conducting DNA tests and are continuing to analyze the handwriting of the two notes to police. Authorities declined to discuss specifics, but one law enforcement official said the results "have been very fruitful."

An official with the Bellingham, Wash., police department said yesterday that a woman acquainted with Muhammad filed a suspicious person's report Nov. 30 that involved Muhammad.

Kristine Sagor, the manager of an apartment complex where Muhammad did occasional odd jobs, told law enforcement authorities that he had asked a gunsmith in the Bellingham area about modifying a rifle so it could be "folded neatly in a small case," her attorney said.

She drove Muhammad to the home of the gunsmith in November, her attorney, Harvey H. Chamberlin, said yesterday. He said Sagor did not wish to be interviewed.

"She remembers him asking if the gunsmith can modify a rifle. She overhears a conversation about cutting the barrel off, modifying the weapon in such a way as to fit into a small case," Chamberlin said.

A few days later, on Nov. 30, she called in a report to Bellingham police. She also alerted the FBI, the Border Patrol and the federal Bureau of Alcohol, Tobacco and Firearms, Chamberlin said. About two months later, after nothing happened, she called the same authorities again. Last week, she was interviewed by the FBI and ATF, her attorney said.

Since last week's arrests, police across the country have been trying to determine whether homicides or other crimes in their localities could be linked to the sniper suspects.

In Baton Rouge, La., where Muhammad grew up, police said yesterday that they want to see whether Muhammad and Malvo might be connected to a series of homicides in the past year.

"We don't feel that there's a strong possibility" that the two are connected to the Baton Rouge cases, "but of course we have to explore that possibility," said Cpl. Mary Ann Godwana, a police spokeswoman.

Muhammad and Malvo were in Baton Rouge this summer, acquaintances and relatives said, and Muhammad had visited at an undetermined time earlier in the year.

Staff writers David S. Fallis, Phuong Ly, Michael E. Ruane, Jamie Stockwell, Lena H. Sun and Josh White, researcher Bobbye Pratt and special correspondent Eric Scigliano in Tacoma contributed to this report.