ROCKVILLE, Md. – Police investigating the Beltway Sniper issued an arrest warrant Wednesday for a 42-year-old former Army soldier they believe has information about the string of terrifying shootings that have left 10 people dead.
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, John Allen Muhammad, should be considered "armed and dangerous" and that he was being sought on a federal weapons charge.
He also cautioned that the public should not assume Muhammad is involved in any of the shootings that have stricken the Washington area since Oct. 2 that have also left three people critically wounded.
Moose identified Muhammad as a 6-foot-1, 180-pound 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. He also said a juvenile may be accompanying Muhammad.
He did not identify the juvenile, but a law enforcement source identified him as 17-year-old Lee Malvo.
Moose also issued another direct message to the sniper:
"Let's talk directly. We have an answer for you about your option. We are waiting for you to contact us."
"You asked us to say 'We have caught the sniper like a duck in a noose.' We understand that hearing us say that is important to you," Moose said. "Let's talk directly. We have an answer for you about your option. We are waiting for you to contact us."
A U.S. official in Washington told Fox News authorities were looking for two "people of interest," Mohammad, formerly connected to Fort Lewis, an Army base south of Tacoma, and Malvo.
Police did not say where they believe the pair might be. They issued an alert for a 1990 blue or burgundy Chevrolet Caprice with the New Jersey license plate NDA-21Z and a 1989 white Chevrolet Celebrity with Maryland plates reading ZWE-510.
Earlier this month, police said they were looking for a burgundy Caprice seen near a fatal Oct. 3 shooting by the sniper in the District of Columbia.
Muhammad's ex-wife, Mildred, was being questioned by the FBI Wednesday, said Adele Moses, who identified herself as the woman's sister. She said Mildred was living with her in Clinton, Md., southeast of Washington.
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.
The FBI searched a back yard in Tacoma that they believe may be related to the probe Wednesday night.
Law enforcement sources told Fox News that search warrants related to the serial sniper case were served in various parts of the country Wednesday evening.
The sources said these multiple warrants included some in the D.C. area and at least one search warrant was executed in Marion, Ala.
The FBI is searching a location near Marion, Ala., known as Camp Ground Zero USA — a place known to train militia groups. FBI sources told Fox News "they are not at liberty to comment" on the investigation and cannot confirm or deny their agents are investigating Camp Ground Zero USA.
Fox News reported Tuesday that a credit card is playing a crucial role in the investigation. Fox News has learned that the credit card apparently was taken following a liquor store robbery in Montgomery, Ala., on Sept. 21.
In that shooting, 52-year-old Claudine Parker was shot and killed. That credit card taken during the liquor store robbery is the same one that the serial sniper wanted officials to transfer $10 million to.
It now seems clear that the search warrants being run in Alabama are somehow connected to this leg of the investigation. We also know that this same stolen credit card was used recently in the Washington, D.C., area.
Montgomery, Ala., Mayor Bobby Bright said federal authorities were investigating whether the fatal shooting there last month was linked to the sniper. No one has yet been arrested after the one woman was killed and another wounded as they walked to their cars after locking up the store.
Moose, who is heading the sprawling investigation, expressed frustration at the failure to make contact despite the sniper's repeated attempts through "notes, indirect messages and calls to other jurisdictions."
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.
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 by tape, and agents swept metal detectors back and forth in a painstaking search.
The 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 property owner consented to the search, 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 soldier 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 were apparently seeking information on a male teenager who once attended the school and an older man. He said both left the area about nine months ago.
Fox News' Ian Christopher McCaleb, Jonathan Serrie, Andrew Hard, and The Associated Press contributed to this report.