AS the Oklahoma City bomb investigation enters its second month, battering rams and helicopters have given way to ballpoint pens and comfortable shoes.
Instead of breaking down doors, federal agents are working regular shifts now: interviewing motel maids, trailing right-wing militants to the grocery store, and sifting mounds of rubble for bits of detonator cord.
But besides tedium, the one-month mark has also brought questions about the performance of federal gumshoes.
Although investigators have said the bombing was the work of several conspirators, only two men, Timothy McVeigh and Terry Nichols, have been charged with the crime, and there is still no sign of the elusive ''John Doe No. 2.''
The evidence implicating Mr. McVeigh seems to mount as the weeks creep by, but the government's case against Mr. Nichols has some soft spots. To make matters worse, a Michigan judge released Nichols' brother, James, on a $5,000 bond -- against the FBI's wishes.
In a series of interviews, federal officials and criminologists say that although the nation's largest-ever manhunt has stumbled at times, it is far too early to pass judgment.
The case, they say, points up both the strengths and limitations of modern police technology.
Given the nature of the conspiracy, says Robert Louden, director of the Criminal Justice Center at John Jay College in New York, the public should not expect it to be cracked in four weeks.
''This is an awfully big country,'' he says. ''The conspirators are likely to be survivalists, militia sympathizers, or others who are comfortable in the woods'' and could hide for years.
Besides, Mr. Louden says, it is not difficult for a fugitive to avoid prosecutors by obtaining fake identity papers, changing appearance, moving through a number of states, and even fleeing the country.
Experts say the size and exposure of the case also complicates matters.
As Louden explains, there are 80 federal agencies with some law enforcement authority. From the Federal Bureau of Investigation (FBI) and the Bureau of Alcohol, Tobacco, and Firearms, (BATF) to the Postal Service and the Department of Agriculture, Louden says, ''conceivably, before it's all over, every one of these agencies could play a role in the investigation.''
Priorities can shift all the time in an investigation like this, even within a given day, says Harvey Burstein, a former FBI agent who teaches at Northeastern University in Boston.
Initially, he says, the overwhelming number of leads, and the sheer number of investigators -- some estimates say as many as half of the FBI's 10,000 agents were involved -- led to a logjam that made it harder for hot leads to reach decisionmakers promptly.
In recent weeks the FBI has trimmed the size of the investigation and installed one veteran, Special Agent Dan Defenbaugh, to coordinate the search. ''It's crucial to have one person in charge,'' Burstein says, ''so that all reports from the field are funneled into one location. That way, when you've got a good bite on something, you can move quickly.''
But Burstein notes that the public seems largely unaware that just as federal agents are looking for more conspirators, they are also building a case against the suspects already in custody. In preparation for its case against McVeigh, federal laboratories are enhancing a security camera image taken moments before the blast, analyzing clothes, shoes, and car parts for incriminating dust or chemicals, and reconstructing the 5,000-pound fertilizer bomb. They are also scouring ''hot zones'' like Kingman, Ariz., where McVeigh once lived.
All in all, law enforcement experts are optimistic. Jessie Jones, a regional spokesman for the BATF, says that the first convictions in the case could happen in less than the 18 months it took federal prosecutors to convict the first bombers arrested in the attack on the World Trade Center in New York.
According to a recent ABC news poll, 85 percent of Americans say they are satisfied with the FBI's performance. John Russel, a Justice Department spokesman, says Attorney General Janet Reno is ''pleased'' with the progress made in the the case.
But there is still a lot of ground left to cover. On Friday, FBI officials announced that Michael Fortier, an Army buddy of McVeigh's, admitted traveling to Oklahoma City with McVeigh to case out the Murrah building. FBI officials said Friday that Mr. Fortier made the statements as part of ongoing negotiations that may lead to a plea bargain in exchange for testimony.
While the announcement bodes well for the government's case against McVeigh, it does not seem to shed new light on other conspirators -- as such, some see it as a public relations ploy.
Federal officials made the announcement following a hearing last week at which defense attorneys for Terry Nichols forced FBI agent Errol Myers to admit that Nichols may have made phone calls from his house in Kansas on the day of the bombing, and that a broken fuel meter agents seized from Nichols' Kansas farmhouse could not have been used in making a bomb.
For now, the investigation continues at a methodical clip, with agents interviewing people, crosschecking names on computer databases, and drawing everything together at an end-of-the-day briefing.
According to Burstein, agents are not concerned with charges that breaks in the case so far, like the arrest of McVeigh an hour after the bombing by an unwitting Oklahoma State Trooper, are the result of dumb luck.
''No matter how lucky you are,'' he says, ''you won't find anything if you're not out there looking.''