Police have started a dialogue with a man they believe is the serialsniper, law enforcement sources said, and yesterday Montgomery County Police Chief Charles A. Moose appealed to the man to call back because his previous message was "unclear."

"The person you called could not hear everything you said," Moose said yesterday afternoon in his third cryptic message since Sunday night. "The audio was unclear, and we want to get it right. Call us back so that we can clearly understand."

Police began delivering a series of tantalizing messages through the media after they found what several law enforcement sources described as a handwritten letter at the scene of the sniper's latest shooting, outside an Ashland, Va., restaurant 80 miles south of Washington.

The sources said police believe they also have spoken to the letter writer by phone at least twice. The sources expressed confidence that they are communicating with the Washington area sniper who has killed nine people and wounded three since Oct. 2 because information either in the phone calls or the letter indicates intimate knowledge of the tarot card left Oct. 7 at a shooting scene in Bowie.

"There is no reason for us to believe it's not from the sniper," said one of the sources, a high-ranking law enforcement officer.

Moose's direct appeal yesterday came on a whirlwind day of highs and lows in the sniper investigation. Early in the day, authorities in suburban Richmond detained two men and seized a white van, raising hopes for a break in the case. But they later determined that the men had nothing to do with the shootings.

Police also said that a white box truck with a .223-caliber shell casing in the back, taken from a rental agency near Dulles International Airport over the weekend, turned out to be unrelated to the case. Finally, ballistics tests conclusively confirmed that a 37-year-old man traveling through Ashland on Saturday was the sniper's 12th victim.

But the most drama came from Moose, who has been the leader of the task force investigating the shootings. His plea for the person to call again came a few hours after he had stood before the cameras and told the person that he would respond to him later in the day.

The tired-looking police chief's veiled messages were the only public hints of an exceptional, behind-the-scenes conversation that appeared to be underway. Although the secretive -- yet gripping -- messages broadcast on live television were not very enlightening to most listeners, police said they would make sense to whomever Moose was addressing.

It was the second time that Moose indicated that police were having difficulty contacting the person who left the note in Ashland. Sunday night, he said police wanted to talk to that person and implored him to call. It is unclear why investigators are having trouble connecting with the person if he is reaching out to them, although some officials have complained about inefficiency in the way police are handling tips and other calls.

Moose's appeal came after police announced that Saturday night's shooting at the Ponderosa steakhouse in Ashland off Interstate 95 in Hanover County is linked to the sniper, the first weekend shooting and the first outside the immediate Washington metropolitan area. In all, there have been 13 shooting incidents in Montgomery, Prince George's, Spotsylvania, Prince William, Fairfax and Hanover counties and in the District.

Sources said investigators also found a shell casing near the Ashland restaurant that matched the shell casing found at the Bowie shooting. That shooting, which wounded a 13-year-old boy outside Benjamin Tasker Middle School, was the only other known sniperattack in which the shooter left a message and a shell casing. Police found a tarot card there with the message, "Mister Policeman, I am God."

The frenzy of activity started over the weekend when police found the letter, which sources said was at least three pages long, contained veiled threats and mentioned a demand for money.

Since then, the man police believe is the sniper has called at least twice, the sources said, and at least once, the male voice said, "I am God."

One of the calls came yesterday morning and was traced to an area along busy Broad Street in Henrico County in the immediate vicinity of an Exxon gas station, several sources said.

Police were staking out the area, and shortly after 8:30 a.m., a white Plymouth Voyager with a luggage rack pulled up and began idling within arm's reach of the receiver of a single telephone directly in front of the gas station.

Police clad in bulletproof vests and carrying assault-style weapons rushed the vehicle and dragged out a man. He was taken into custody.

Eliasar Morales, 43, a maintenance worker at a Citgo station across the street, said he was opening up the drive-through carwash when he saw police subdue the man.

Moments later, he saw officers detain a man who was using a pay phone at his station. Morales said he recognized him as a regular customer who often stopped in to buy phone cards.

"The cops just grabbed him," Morales said. "He just said, 'I don't speak English.' " 

Hanover County Sheriff V. Stuart Cook soon announced that the two men were being questioned in relation to the series of shootings, sending hope across a region gripped with fear and frustration over the attacks.

But later in the day, police released them, saying they had nothing to do with the shootings. Authorities said one was a 24-year-old Mexican and the other a 35-year-old Guatemalan who are in the United States illegally.

"These two mopes were just in the wrong place at the wrong time," said a law enforcement official.

After they were cleared of involvement in the attacks, they were turned over to the Immigration and Naturalization Service. "The individuals are in INS custody and are being detained pending proceedings for immigration violations," said Bill Strassberger, an agency spokesman. He said the men would probably be deported.

Law enforcement officials said the detentions were the prudent course of action and added that they didn't think it would harm Moose's attempts at communication.

Eric W. Hickey, a professor of criminal psychology at California State University at Fresno and author of "Serial Murderers and Their Victims," said that given the danger of the sniper, police must act as aggressively as possible. "The public would go crazy if they found out they [police] laid back," he said.

But others said they thought that the actions may have been premature. "The problem now is that they, for lack of a better word, tipped their hand to the sniper," said former D.C. homicide detective J.T. McCann. "You lose your best chance of getting this guy if you move in too quickly or you move in on the wrong guy."

Once again, in a case that has confounded detectives for almost three weeks, hopes raised in a day were dashed.

"The emotions have run the gamut," said state Sen. Bill Bolling (R), whose district includes Hanover County and a portion of Spotsylvania. "This morning, everyone was hopeful they had a significant break that would lead to the capture of the person committing these acts. As the day goes on, you learn perhaps it wasn't what people hoped it was. . . . We'll be on this emotional roller coaster more than once."

Each shooting has grated anew on raw nerves that have led people to change the way they go about some of the most basic daily chores.

In the Washington area, most schools are still in lockdown, confining children to indoor activities.

Richmond area schools have decided to remain closed for a second day following Saturday's shooting. Hanover schools spokeswoman Dale Theakston said the superintendents of the area's districts initially planned to hold classes yesterday under lockdown. But after consulting with local law enforcement officials and receiving many phone calls from worried parents, they decided instead to close, she said.

Del. Frank D. Hargrove Sr. (R-Hanover) said the decision was based on law enforcement information about a possible "imminent danger in that area, not necessarily to schoolchildren."

Independent schools followed the lead of area public school districts, which also include Richmond City and Goochland and Chesterfield counties. Gussie Bannard, head of St. Catherine's, an independent school in Richmond, sent an e-mail to parents saying school would be closed based on the FBI's "strong urging" -- though school spokeswoman Carol Billingsley said law enforcement officials gave no orders.

Also yesterday, Matthew M. Dowdy, 37, who authorities said provided a bogus account of the Oct. 14 fatal shooting in front of the Home Depot at Seven Corners, continued to be held without bond after an appearance in Fairfax County General District Court.

Authorities said that Dowdy, of Falls Church, gave them a fabricated description of the gunman, his weapon and a cream-colored van he said the man was driving. Yesterday, Fairfax County Deputy Commonwealth's Attorney Raymond F. Morrogh said surveillance cameras showed that Dowdy was inside Home Depot when the shot was fired.

"His lies resulted in a massive waste of resources," Morrogh said in court. "At the time he lied, he knew we were dealing with a serial killer. He was not in a position to see any of the things he said he saw."

Morrogh said Dowdy provided false information to authorities on three separate occasions, but he did not comment on a motive. He said Dowdy has an extensive criminal record that includes seven felony convictions.

Dowdy, who will be assigned a court-appointed attorney, is scheduled to go to trial Nov. 18 on a misdemeanor charge of providing a false statement to a law enforcement official. The charge carries a maximum penalty of six months in jail and a $1,000 fine.

At a Richmond hospital, the sniper's latest victim was listed in stable condition as he recovered from two surgeries within 24 hours. Surgeons, who removed the man's spleen and parts of his pancreas and stomach, said he is a strong man whom they expect will someday be able to live a normal life.

His wife issued a message through the hospital thanking people for their prayers, which she said had been "a bright ray of hope and comfort."

"Please pray also for the attacker, and that no one else is hurt."

Contributing to this report were staff writers Jo Becker, Patricia Davis, Christian Davenport, Dan Eggen, Steven Ginsberg, Maria Glod, Hamil R. Harris, Spencer S. Hsu, Tom Jackman, Allan Lengel, Phuong Ly, R.H. Melton, Elaine Rivera, Susan Schmidt, Michael D. Shear, Mary Beth Sheridan, Jamie Stockwell, Craig Timberg and Josh White.