After September 11 and the anthrax attacks, there had been speculation that terrorists were behind the wave of sniper attacks which killed 10 people in the past few weeks.
However, a letter found in a park adjacent to the scene of the tenth and final killing, threatened further violence and demanded that $10m be wired to a domestic bank account.
Law enforcement sources said last night that the letter specified the money be wired in such a way that the author would be able to withdraw all the money from any automated teller machine in the world.
In the event, it didn't come to that. As John Muhammed and Lee Boyd Malvo slept in a rest area at the side of a motorway in Maryland, a witness recognised their vehicle from police warnings on television.
The police moved in and arrested both men without resistance. Finally, the sniper attacks that have killed 10 and gripped the US nation in an unfolding plot of terror were over.
The two - one a former soldier - have been linked to the wave of serial shootings through a fingerprint traced to an Alabama double-shooting.
The men were arrested without incident at 3:19am off eastbound Interstate 70, west of Frederick near Myersville, about 50 miles northwest of the Washington DCl, said Larry Scott, an agent for the Federal Bureau of Alcohol, Tobacco and Firearms.
John Allen Williams, 41, also known as John Muhammad, and Lee Boyd Malvo, 17, who lived together at a Tacoma, Washington, house before moving cross-country, were being sought for questioning last night. They were believed to have little or no money and may have been frequenting inexpensive hotels and homeless shelters.
Police had said they might be travelling in a 1990 burgundy Chevrolet Caprice, with New Jersey license plate NDA-21Z. The men arrested early yesterday were in a car that matched that description, said Major Greg Shipley of the Maryland State Police, after it was spotted by a motorist and an attendant at a rest stop.
"I don't know what their reaction was," Shipley said. "It wasn't an aggressive one." The men were not immediately charged in the attacks, but authorities made clear the arrests were considered pivotal. A law enforcement source close to the investigation told the Associated Press: "I'm confident these are indeed the people" sought in the killings. Montgomery County Police Chief Charles A Moose had said at a midnight briefing that police were looking for Williams and a youth with him, and that Williams should be considered "armed and dangerous".
Stopping short of identifying Williams as a sniper suspect, Moose issued another plea to the killer, asking him to contact police. The chief also satisfied the killer's apparent request to say an enigmatic statement over the airwaves:
"You asked us to say: 'We have caught the sniper like a duck in a noose'," Moose said, "We understand that hearing us say this is important to you; however, we want you to know how difficult it has been to understand what you want because you have chosen to use only notes, indirect messages and calls to other jurisdictions." Moose then encouraged the sniper to call at a private toll-free number established for him or to write to a post office box in Gaithersburg. As it transpired, the police found the two men first. Several federal sources told the Seattle Times that Muhammad and Malvo may have been motivated by anti-American sentiments in the wake of the September 11 attacks.
Both were known to speak sympathetically about the men who hijacked jetliners over Washington, New York and Pennsylvania, the sources said. But neither man was believed to be associated with the al-Qaida terrorist network Their whereabouts in the area throughout the sniper attacks is unclear. However, police in Baltimore logged a report indicating that on October 8 Williams had been in Baltimore and had a run-in with city police, a law enforcement source said.
The tip that led the task force to investigate Williams came from someone in the Tacoma area who called police. Williams was wanted on an outstanding shoplifting warrant filed by Tacoma police and on a federal firearms warrant that police say is unrelated to the shootings in the DC suburbs. Another break in the case came when the killer made a remark that helped police zero in. He told police they should "check with the people in Montgomery", or words to that effect, a law enforcement source said.
While they were initially unsure what the sniper meant by that remark, police eventually hit upon the right avenue that led them to a critical clue.
They checked every shooting that occurred in recent months in Montgomery, and found a double-shooting outside a liquor store there on September, 21 that involved .223-caliber ammunition - the same used by the Washington-area sniper, the law enforcement official said.
In that shooting, one woman was killed when she was shot in the back and another woman was critically injured.
Employee Kellie Adams, 24, told The Sun she was shot in the neck just after she left the store with her co-worker about 7.20pm. A police officer saw a man running away and gave chase - at one point coming within two feet of the suspect - and police created a composite sketch of a black man. Later found at the scene of the crime, originally thought to be a robbery gone bad, was a flier or another piece of paper that bore Malvo's fingerprint, the source said.
Police traced Malvo to a Tacoma house, where he had been living with Williams, a former soldier at nearby Fort Lewis.
Montgomery Police Chief John Wilson said the composite sketch of the suspect in the Alabama shootings had "some very good similarities" to one of the men arrested in the sniper investigation, but he also added that ATF agents had told him the gun used in that incident was not the same as the one used in the sniper attacks.
Yesterday, dozens of police and federal agents searched the house and its rear yard, where they hauled off an uprooted tree and a nearby stump that might have been the targets of shooting practice. An ATF spokesman said the stump would be brought to the agency's lab in Rockville, Maryland, for ballistics testing. Newspapers reported that Williams was stationed at Fort Lewis in the 1980s, served in the Gulf War and was later stationed at Fort Ord, California.
Several hours after the arrests spokesmen at the Pentagon said they had no information and referred calls to the agencies handling the case. Defence officials had said last week that, at the investigators' request, the army was searching its records of people trained as snipers A neighbour, David Burnson said he recalled occasionally hearing gunshots in the neighbourhood, but was uncertain which property they came from. The search was under way as Montgomery County police were planning a 6pm appearance before reporters - an arrangement that in recent days has served as a televised method of communication with the sniper.
After the appointed hour passed, police spokeswoman Nancy Demme said no statement would be forthcoming because of "developments in the case that have taken us down roads we want to investigate further."
News of a break in the case raised hopes across the region that has lived in fear for three weeks.
"I hope they've caught him. It's time for the violence to stop," said Amy Mihulski of Alexandria, Virginia, who was leaving a restaurant in Manassas behind the Sunoco gas station at the time of the shooting there on October 9.
"It's been horrible. I walk my dog and stop every time I see a white van."