Rockville, Md. ? Police issued an arrest warrant Wednesday for a former Army soldier they believe may have information about the sniper shootings that have left 10 people dead in the Washington suburbs. Investigators also delivered another message to the sniper, complying with a request to say: “We have caught the sniper like a duck in a noose.”

Montgomery County Police Chief Charles Moose said the man wanted for questioning, John Allen Muhammad, was being sought on a federal weapons charge and should be considered “armed and dangerous.”

However, Moose said no one should assume Muhammad, 42, is involved in any of the shootings that have stricken the Washington area since Oct. 2.

The lead came on a busy day that saw the investigation spread literally across the country to Tacoma, Wash., where FBI agents converged on a home with metal detectors and chain saws.

The Pierce County, Wash., Sheriff’s Office said Muhammad was once stationed at Fort Lewis an Army post south of Tacoma that provides some of the most intense sniper training in the military.

Across the nation’s capital and its suburbs, worried parents sent children off to schools Wednesday with extra-tight hugs, defying the sniper’s warning that children are not safe “anywhere, at any time.” Thousands kept their kids at home.

And police also said ballistics and other evidence had confirmed the bus driver shot to death on Tuesday was the sniper’s 13th victim in the three-week rampage that has also left three people critically wounded.

Message for a killer

FBI investigators work with metal detectors and a backhoe in the back yard of a house in Tacoma, Wash. The agents, acting Wednesday on information from the sniper task force, were seeking evidence related to ammunition in the sniper case in the Washington, D.C., area.

Moose, who is heading the sprawling investigation, issued another direct message to the killer via television late Wednesday. He expressed frustration at the failure to make contact despite the sniper’s repeated attempts through “notes, indirect messages and calls to other jurisdictions.”

“You have indicated that you want us to do and say certain things. You’ve asked us to say, ‘We have caught the sniper like a duck in a noose.’ We understand that hearing us say this is important to you,” Moose said.

Then he said: “The solution remains to call us and get a private toll-free number established just for you.” If that happens, Moose said, “we can offer other means of addressing what you have asked us for.”

The latest message believed to be from the killer was a letter found not far from where bus driver Conrad Johnson, 35, was shot Tuesday, two law enforcement sources told The Associated Press on condition of anonymity.

The message reportedly demands $10 million the same request sources say was made in a letter found at another shooting site Saturday.

Moose identified Muhammad as a black male who also goes by the name John Allen Williams, and authorities released a photograph showing a clean-shaven man with closely cropped hair.

Moose said Muhammad may be traveling with a juvenile, identified by a law enforcement source as 17-year-old Lee Malvo. The relationship between Muhammad and the teen was not clear.

Search in Tacoma

In Tacoma, FBI agents spent hours at a rental home, eventually carting away a tree stump from the yard and other potential evidence in a U-Haul truck. The back yard was divided into grids, and agents swept metal detectors back and forth.

The FBI agents, acting on information from the sniper task force, were seeking evidence related to ammunition, a senior law enforcement official in Washington said on condition of anonymity.

FBI spokeswoman Melissa Mallon said the search was consented to by the property owner, but she refused to say why agents were there.

“There’s no immediate danger to anyone in this neighborhood,” she said.

Pfc. Chris Waters, a Fort Lewis private who lives across the street from the home, said he called police after hearing gunshots in the neighborhood nearly every day in January.

“It sounded like a high-powered rifle such as an M-16,” he said. “Never more than three shots at a time. Pow. Pow. Pow.”

Dean Resop, who lives a block away, said “quite a few tenants” had been in and out of the home.

“Makes you want to watch your neighbors closer,” said Resop, who has lived in the area seven years.

FBI agents also visited Bellingham High School, 90 miles north of Seattle, on Wednesday. Mayor Mark Asmundson told the Bellingham Herald the agents apparently were seeking information on a male teenager who once attended the school and an older man. Asmundson said both left the area about nine months ago.

Schools affected

Investigators waited three days to reveal the sniper’s threat against children, which was contained in a letter found after a shooting Saturday in Ashland, Va.

Michael Bouchard of the Bureau of Alcohol, Tobacco and Firearms insisted vital information was not being withheld.

“We’re all parents and are certainly concerned about the safety of our kids and of our co-workers,” he said. He said if information is released too early, “it inhibits our ability to do the job we need to be doing.”

Schools across the region reported below-average attendance Wednesday.

“I’m not afraid of the sniper,” said 17-year-old Heather Willson, a senior at Albert Einstein High School in Montgomery County. “I mean, I don’t see any reason why he’s going to change his tactics now and come inside and start shooting up students.”

Schools in the Richmond, Va., area opened Wednesday for the first time this week, but attendance was lighter than usual.