A military-style rifle allegedly seized from two suspects in the Washington area sniper attacks was used in at least 11 of the 13 shootings, authorities announced last night, signaling the end of a three-week siege in which a seemingly faceless gunman terrified the region by killing indiscriminately.

"We have not given in to the terror," said Montgomery County Police Chief Charles A. Moose, a leader of the law enforcement task force hunting for the sniper. "Yes, we've all experienced anxiety. But in the end, resiliency has won out."

The fear that had pervaded the region -- forcing schoolchildren behind locked doors and turning mundane outdoor ventures into a test of nerves -- began to dissipate as news of the day's events filtered out. By last night, police had put a face to the man they suspect was responsible for the deaths of 10 people.

The two suspects are an apparently penniless Army veteran of the Persian Gulf War and his teenage companion, whose strange cross-country journey from Washington state ended early yesterday at an Interstate 70 rest stop in Maryland. The pair, arrested while sleeping in a car, had not been charged in the attacks as of last night. But authorities left no doubt that they intend to prosecute John Allen Muhammad, 41, and John Lee Malvo, 17, in the deadly series of stealth attacks, which began Oct. 2.

"Tonight, people in the Washington metropolitan region are breathing a collective sigh of relief," said Montgomery County Executive Douglas M. Duncan, appearing with law enforcement officials last night at a news conference in Rockville, where the manhunt for the Washington area sniper was based.

Moose said that "prosecutors from all the involved jurisdictions" will meet "to discuss the filing of charges" against the two. Meanwhile, Muhammad was ordered held without bail yesterday on a federal weapons charge, and the youth is being detained as a material witness in the sniper investigation.

Much about the pair remains a mystery, including any motive for the attacks. The two had been living in Washington state, and it is unclear why they allegedly chose to make the nation's capital and its suburbs their killing ground. Their relationship is also unclear, and it is unknown whether authorities suspect one or both of having pulled the trigger in the attacks.

Contrary to a theory that prompted wide speculation, no evidence has emerged that Muhammad or Malvo is connected to a terrorist organization, law enforcement sources said. But detectives are examining reports from acquaintances that Muhammad may have sympathized with Osama bin Laden and applauded the Sept. 11, 2001, attacks on the World Trade Center and Pentagon.

According to court papers connected to the federal gun charge, Muhammad fantasized about the damage he could do with an assault rifle equipped with a silencer.

Robert Holmes, a former roommate in Tacoma, Wash., told federal authorities that during a visit four months ago, Muhammad showed off an AR-15 assault rifle with a scope, which he carried in an aluminum briefcase. Muhammad and "an associate" said they were taking the gun to the range to "zero it," or align the scope so the rifle would shoot accurately.

Holmes said Muhammed and his companion had a book on making a silencer and said, "Can you imagine the damage you could do if you could shoot with a silencer?"

A Bushmaster XM-15 rifle, which fires .223-caliber rounds and was found in the suspects' vehicle, has been "forensically determined to be the murder weapon," said Mike Bouchard of the federal Bureau of Alcohol, Tobacco and Firearms.

Police said they could link the rifle to 11 of the 14 shooting incidents, in which 10 people were killed and three were wounded in the District and in Montgomery, Prince George's, Spotsylvania, Prince William, Hanover and Fairfax counties. In one shooting, no one was injured. Bullets or fragments from two shootings were too badly damaged to be tested, officials have said.

At the news conference, Duncan recited a roll call of the dead, asking for a moment of silence "to reflect upon and honor the memory of these innocent victims, in addition to the other three victims who are continuing their recovery."

"James Martin. Sonny Buchanan. Premkumar Walekar. Sarah Ramos. Lori Lewis Rivera. Pascal Charlot. Dean Meyers. Ken Bridges. Linda Franklin. And Conrad Johnson."

Although Muhammad and Malvo have not been charged in the shootings, "just because people haven't been formally charged doesn't mean there isn't evidence to charge them," Montgomery County State's Attorney Douglas F. Gansler said in an interview. "There's a great sense of relief among law enforcement that the people apprehended have been definitively linked to these particular crimes.

"At this point, we have every intention of seeking the death penalty in this case for the adult," he added.

Malvo is too young to be sentenced to death in Maryland, but Gansler said a sentence of life without parole is "certainly very much on the table."

Prosecutors from Maryland, Virginia (where juveniles are eligible for the death penalty) and the federal government were maneuvering yesterday for the first chance to try the sniper case, with a high-level debate centering on which venue has the best chance of carrying out the death penalty.

The pair were arrested about 3:30 a.m. yesterday at a Frederick County rest area along Interstate 70 as they slept in a blue 1990 Chevrolet Caprice, which authorities said had been modified so that a rifle could be fired by a person prone inside the trunk.

Sources said that in addition to finding the gun in the car, police found a silencer, duffel bags and a rifle tripod.

In Baltimore yesterday afternoon, as SWAT team members with automatic rifles stood guard in the lobby of the Garmatz Federal Courthouse, U.S. Magistrate Judge Beth P. Gesner ordered that Muhammad be held on charges that his possession of a firearm violated a restraining order obtained by his former wife in Washington state last year.

A handcuffed Muhammad entered the courtroom wearing a short-sleeved green prison jumpsuit and blue prison-issue slippers. He looked subdued and bowed his head slightly as he made his way to the defense table. His wrists were uncuffed and he sat beside his attorney, federal public defender James Wyda.

The judge asked him, "Have you taken anything into your body that would prevent you from understanding these proceedings?" Muhammad leaned over to whisper to Wyda before answering.

"I know where I'm at, and I know what I'm doing," Muhammad said.

Because Malvo is a minor, the public was not allowed to attend his court proceeding.

The arrests brought relief to authorities, who had appeared to grow increasingly frustrated as the sniper eluded a massive manhunt and taunted police in angry letters and other messages.

The sniper case drew attention around the globe. For three terrifying weeks, residents of Washington and its suburbs crouched at gas pumps, pulled the blinds on school windows, and sat snarled in traffic while police shut down major arteries and searched white vans that suddenly seemed to be everywhere.

Yet even as Montgomery schools announced that they would resume normal outdoor activities and school trips today, many weary residents felt only a tentative sense of relief. Some said that although they hoped the sniper had finally been caught, they would relax only gradually.

"I feel 90 percent better today," said one parent, still so leery of the sniper that she spoke on the condition that her name and that of her daughter's school not be published.

Investigators are just starting to delve into the the background of Muhammad, a Louisiana-born, twice-divorced convert to Islam who, in his 15-year Army career, never rose above the rank of sergeant. Malvo, also a focus of intense law enforcement scrutiny, came to the United States from Jamaica by boat as part of a smuggling operation run from Haiti and lived in a homeless shelter in Bellingham, Wash., according to the Immigration and Naturalization Service.

The two apparently met at a nearby YMCA.

Police had been on the lookout not for a person, but vehicles described by witnesses: a white van, a box-shaped delivery truck, a cream-colored Toyota. That now appears to be the main reason why the blue Caprice in which Muhammad and Malvo were caught had earlier failed to attract attention.

Last Thursday, operators staffing police tip lines received a call from a man purporting to be the sniper, sources said. They said the caller claimed responsibility for a robbery and slaying that police later determined had occurred in Montgomery, Ala.

The next day, two men called a priest in Ashland, Va., ranting and mentioning the Alabama slaying, a spokesman for the Richmond Diocese said. The priest did not take them seriously and did not report the incident, the spokesman said. After a man was shot and wounded in Ashland on Saturday, investigators showed up at the church on Sunday, and the priest told them about the call. It is unclear how police learned that the men had some connection to the church.

Then, last week, authorities received a call from someone in Tacoma who suspected that Malvo could be the sniper. The tipster said someone had taken target practice with a gun in the back yard of a Tacoma home.

Members of the task force investigating the sniper attacks contacted authorities in Alabama and quickly learned of a Sept. 21 shooting at a liquor store that had left one woman dead and another badly wounded, police in Alabama said.

A fingerprint taken at the scene from a magazine about munitions and weapons was traced to Malvo, whose prints were on file with the INS.

"This guy hung himself with his bravado" by making reference to the Alabama robbery, a law enforcement source said. "The fingerprint from the liquor store is what nailed it and allowed us to tie it all together."

The investigation of Malvo led police to Muhammad.

At 12:47 a.m. yesterday -- after police released a photo of Muhammad and a description of his car -- a motorist in Maryland called Frederick County authorities to report a car matching that description was parked at the rest stop on Interstate 70 in Frederick County, said Maj. Greg Shipley, a Maryland State Police spokesman.

By 1 a.m., a helicopter was landing at Richard Montgomery High School off Route 355 in Montgomery County. A group of FBI agents and Montgomery County officers in black SWAT gear climbed into the helicopter and headed toward Frederick.

Awaiting the SWAT teams, police in Frederick blocked the entrance and exit to the rest stop. About 3:30 a.m., SWAT officers surrounded the car and took Muhammad and Malvo into custody.

According to Shipley, the two did not resist arrest. However, a law enforcement source said that when several officers approached the car, they shattered two of the car's windows. The arrest was accompanied by "a ton of screaming," the source said, though it was unclear by whom.

Muhammad, a native of Baton Rouge, La., was born John Allen Williams on Dec. 31, 1960. He changed his name last year, although he had converted to Islam about the time of his divorce from his first wife 17 years ago.

Muhammad had an encounter with area law enforcement as early as Oct. 2, the day of the first fatal shooting, when he was pulled over by police in Montgomery County, a source said. The next day, when the sniper killed four people in Montgomery County in the morning and another in the District at night, Muhammad was stopped by police in the District, the source said.

Computer checks of his New Jersey license tag came up clean, and, since the traffic violations did not warrant arrest, he was allowed to proceed on both occasions, sources said. The license tag also was captured by a camera in Fairfax County after the car's driver ran a red light.

A federal law enforcement source said that the Justice Department would oversee the decision-making process on where to prosecute the cases.

"It's not who has jurisdiction, but who goes first," said Gansler, the Montgomery state's attorney. "The question is really what order people would be prosecuted in. We're all in it together. These people [the snipers] violated the social contract of all of these jurisdictions in a very violent way and should be held accountable in all of the jurisdictions."

Last night, as the three-week drama appeared to be at an end, Moose spoke of the suspects, of the dead and of those left behind.

"My heart goes out to the victims and the families in these shootings," he said. "So we will never forget. We'll never know their pain, and we only wish we could have stopped this to reduce the number of victims."