Reluctance and difficulties in sharing information among the growing number of agencies investigating the serial sniper case and the FBI's problems handling thousands of phone tips are slowing and hampering the probe, numerous law enforcement officials say.

The investigation's information-gathering effort is so unwieldy that even the suspected sniper failed in repeated efforts to get through to authorities over the weekend on a special telephone tip line that has been swamped with calls since the shootings began, FBI sources said.

Law enforcement officials across the region have repeatedly stressed the cooperative spirit of their joint task force. Nevertheless, from the street to the executive offices, they say they are struggling to get the information they need about everything from road closures to a profile of the sniper and theories about his motives.

With so many federal agencies and local police departments consumed by the investigation, information sharing was perhaps certain to be a confounding problem, particularly because authorities want to carefully guard information that only the sniper could know or that could lead them to the killer.

"It's a tough situation. You can't share everything you know all the time," said one ranking law enforcement official. "When you have the contents of the note, do you broadcast it immediately or do you work with it for several hours? I don't think it's easy to make those calls."

Local law enforcement officials said that concern about leaks to the media has become so great that important information about thesniper investigation is not being shared with the people who need it most: the street detectives working each shooting.

"We're not in the information loop," said one local law enforcement source, who added that normal investigative conventions have largely been thrown out the window. "If we're going to be a part of this, we want all the information we can get. Information, such as communications a suspect might be having with authorities, is a vitally important thing to have in any investigation." Like most of the people in this article, he asked that his name not be used because he did not want to hinder the investigation.

Moreover, the sheer size of the ever-growing investigation -- involving thousands of police officers, detectives and federal agents and encompassing two states and the nation's capital -- makes it difficult to get information when it does become available, they said.

Part of the problem, several officials said, is that detectives, agents and prosecutors do not know where to turn. "What I honestly don't know is who is in charge," a police official said.

While Montgomery County Police Chief Charles A. Moose remains the public face of the investigation, several law enforcement and government officials said federal agencies are making all the important decisions. Calls to federalize the investigation are being ignored because there already is so much federal involvement, they say.

But the coordination problems are leading many investigators to say they cannot get their arms around the information they need.

"Every different jurisdiction has its own little thing going on," said one frustrated FBI agent.

There is no way to marry or even track leads that may be related. They are phoned in to a central FBI tip line and then ferried out to the police departments. "They can have two separate investigations going of the same person," the FBI investigator said.

Investigators need to guard information closely if they hope to negotiate with the sniper, officials said, a situation that is bound to ruffle feathers and leave some people in the dark.

"How do you share it? With whom do you share it? From whom do you withhold it?" one senior federal law enforcement official said. "Every shooting brings in a new county and a new chief of police."

Already, there are numerous task forces in the region dedicated to the same goal: hunting down the sniper. There is the task force in Montgomery and additional ones in Northern and Central Virginia.

Gary M. Bald, special agent in charge of the FBI's Baltimore Field Office, which oversees Montgomery, said yesterday that the cooperation among local and federal officials is unprecedented: "We feel very confident that the platform we've developed and the cooperation we've received from other jurisdictions is exactly what we need. The level of cooperation is 100 percent."

Whatever the good intentions, the strains are apparent to those inside the investigation. "Everybody is yelling at everybody for not sharing information," particularly on conference calls among police chiefs and agency heads, said one FBI manager.

One of the most public examples of that strain came Monday when police in suburban Richmond swarmed a white van and detained its driver at a gas station phone booth even as Moose went on television to send a message to the suspected sniper.

Sources said task force members did not learn of the detention until they heard the White House announce it at a televised news conference. Maryland investigators called it "a rookie move" that tipped their hand. Asked about it yesterday, Moose chose his words carefully: "I would just have to defer any questions about the activity in Henrico County to that police department."

Lt. Tom Shumate, spokesman for Henrico County police, did not return a call late yesterday.

Earlier in the investigation, Moose became livid after the media learned that the killer left a tarot card at the site of a school shooting in Bowie. He was more subdued later, saying that finding the sniperwas the important goal.

Some of the more frustrating problems are at the FBI's toll-free tip line that is publicized nationwide. A caller believed to be the sniper"tried to call four times over the weekend. Three times he couldn't get through. One time he was blown off," an FBI source said.

The tip line had generated 67,215 calls as of midnight Sunday. A small number of the most urgent calls are flagged for immediate action and handed to investigators. The vast majority of the leads take time to pursue, law enforcement sources said, partly because of the FBI's method of receiving and disseminating the information.

Authorities said information is taken down by hand on forms that make multiple carbon copies. Copies are sorted and marked "immediate," "priority" or "routine." Tips that concern Montgomery County are put in one pile, Fairfax in another, Richmond in a third. FBI employees then drive the paperwork out to police in those locations.

The system handling the huge volume of leads, dubbed "Rapid Start" in the days after Sept. 11, is anything but that, say some police and FBI sources who have called it "Rapid Stop." A senior FBI official familiar with the system acknowledged its shortcomings. "Rapid Start" is not suited for a multijurisdictional crime investigation, he said. "Rapid Start was designed for a single event, a single [FBI] office."

On Monday, administrators decided that information from every call must be taken down, even though the majority are not likely to be productive. Many come from people offering theories about the case. The FBI acknowledges that generating a report on every call will slow the process, but it also ensures that there is a record of all calls, which could prove useful later.

But for now, local law enforcement officials remain concerned that they have the information they need to do their jobs.

For example, law enforcement sources said federal investigators surveilled a pay phone in Prince William last week after they received what they believed to be a call from the sniper.

Prince William County police were not involved in the surveillance, and some authorities in the county did not learn of the operation until this week.

In addition, ballistics tests on the bullets found at the crime scenes have not been shared with local prosecutors.

Instead, lots of information is being sent to the task force headquarters, and almost none is coming back to the local agencies.

"It's almost embarrassing how little we know," said one law enforcement official.