The bullet that seriously wounded a Spotsylvania County mother of two while she was loading packages into her minivan outside a mall Friday was fired from the same gun used to kill at least four of the six victims in the series of sniper shootings in Montgomery County and the District, authorities said last night.

"The forensic evidence has shown us that their shooting is linked to the Montgomery County shootings, linked to the D.C. shooting," Montgomery Police Chief Charles A. Moose said of the Virginia case. The conclusion means that five of seven shootings since Wednesday, in which four people were killed, have been attributed to a single high-powered, .223-caliber rifle.

The finding also widens the geographical scope of the shootings, from roughly a five-mile area in Montgomery County and the District to include a largely rural community about 50 miles south of Washington. Police believe that in each shooting, a single shot was fired from a long distance at an unsuspecting victim by an assailant who quickly disappeared.

The victim's van, which contained the bullet that ripped through the woman, was taken to a laboratory set up in a Montgomery County police facility by the federal Bureau of Alcohol, Tobacco and Firearms. The bullet, or its fragments, was analyzed at the ATF's lab in Rockville. The 43-year-old victim was in stable condition last night at Inova Fairfax Hospital, authorities said.

Also yesterday, police said they were questioning a Rockville man who had been reported missing along with a rifle that fires the same kind of bullets used in the attacks. But after initial high hopes that they had found a strong suspect in the attacks, authorities last night all but ruled out the possibility that the man had carried out the shootings.

"I'm not convinced that there's anything we can say that completely clears anyone until we bring the suspect or suspects into custody, get an indictment and get a conviction," Moose said. But he said the man had returned the rifle to the store where he purchased it, and the firearm has since been resold.

The rifle "has nothing to do with our situation," Moose said. What had looked to be a break in the case early in the day turned out to be a disappointment. "He certainly did generate a lot of attention, a lot of energy," Moose said. "And that has now come to closure."

As dusk fell last night in the woman's neighborhood in Spotsylvania County, which lies about halfway between Washington and Richmond, neighbors arrived with covered dishes at her home, and detectives and the sheriff's department made a brief visit.

About 7 p.m., the woman's husband arrived home from the hospital and told a waiting reporter that the family would have no comment. Asked how his wife was doing, he replied, "She's serious, is how she's doing."

Neighbors in the subdivision of 50 luxury homes described the woman, her husband and their two sons as an all-American family.

Authorities declined to identify the wounded woman because they consider her a witness. The bullet that struck her went through the lower-right side of her back, exited under her left breast, then lodged in the back of her minivan.

The Virginia attack occurred at 2:30 p.m. Friday at Spotsylvania Mall in front of a Michaels craft store, authorities said.

Like the Montgomery and District homicide victims, the Virginia woman was performing an everyday chore. Authorities believe the Montgomery attacks were preceded by a shot that was fired Wednesday night into a Michaels store in Aspen Hill that did not hit anybody.

In Montgomery, one victim was vacuuming her minivan at a Shell gas station in Kensington; one was pumping gas at a Mobil station in Aspen Hill; one was walking in the parking lot of a grocery store in Glenmont; one was mowing a lawn near Rockville Pike; and one was sitting on a bench near the Leisure World retirement community. In the District attack, the victim was shot in the chest about 9:20 p.m. Thursday while standing at a street corner near stores on Georgia Avenue NW.

The man being questioned by police last night, Robert G. Baker III, 33, of Rockville, was being held on a Florida auto-theft warrant, police said.

Late Friday, the North Carolina Highway Patrol broadcast a bulletin issued by the ATF that said Baker, a former resident of Raleigh, N.C., had been reported missing by his family on Monday and was "armed with a 40 caliber handgun and a .223 rifle."

The bulletin also said there were "concerns that if Baker was involved in either of the shootings in MD and DC, including the incident in [Virginia] Friday evening, that Baker may be moving south."

But he did not own a vehicle similar to the white cargo truck that a witness reported seeing speed away from one of the Montgomery shooting scenes Thursday.

"I would just like to express the fact that Mr. Baker's vehicle is a dark blue GMC pickup truck with a toolbox in the back," Moose said. "Never has been white, never has been associated with the white box truck we've been talking about."

D.C. Police Chief Charles H. Ramsey said two D.C. detectives had been put on Montgomery County's investigative task force. In the city, detectives spent the weekend talking to witnesses -- who uniformly said they saw no sign of a gunman Thursday night -- and looking for surveillance footage from the area around the shooting site.

Montgomery police continued to work a tip line that has received more than 2,500 calls, producing what police said were about 600 leads worth pursuing; 100 police officers are working on the case, along with 50 federal investigators.

Moose said the FBI has still not completed a psychological profile of the gunman. FBI agents from the Joint Terrorism Task Force in Washington also were working with Montgomery police to determine whether there was a connection between the local shootings and terrorist activity. Law enforcement sources said yesterday they had found no such link.

Fairfax County police arrested Baker yesterday afternoon at a motel south of Alexandria after receiving a call from someone who alleged that Baker had stolen a car, a police source said.

The tipster said authorities could find Baker at a Red Roof Inn on Route 1. The arrest was made after a stakeout there.

Officers impounded the car Baker had been driving but found no gun or rifle, according to the source.

Baker was being interviewed by Fairfax and Montgomery officers last night at the Mount Vernon police substation, the source said.

Montgomery police first expressed interest in Baker on Friday afternoon when a detective issued a broadcast to local police officers about a missing armed man identified as Baker, adding at the bottom of that broadcast the department code indicating a murder suspect. Friday night, Montgomery police sent out another bulletin correcting the first, saying the missing person was not a murder suspect.

"We don't have the right to tarnish someone's name, to tarnish someone's reputation," Moose said.

"We've seen situations in recent history where people have had their lives altered, reputations damaged beyond repair. We don't want that to happen here," Moose added.

Police said Baker surrendered without incident.

Residents along the Rockville cul-de-sac where Baker's home is said ATF agents and police officers had been to the sedate, tree-lined neighborhood Friday night and Saturday morning and were seen going in and out of the house.

A man at Baker's home who identified himself only as a family friend said yesterday morning that there is "no way [Baker] is responsible" for the shootings.

"There's a 100 percent chance the cops will clear him. I'm sure of that," said the man, who was standing outside the two-story red brick and wood home. "The accusations are so absurd that right now, we're just trying to figure out what we need to do to fix the damage done to his name."