At the water cooler, on the message boards, everybody's got a theory.
One of the peculiar consequences of the Washington, D.C.-area sniper case is that it has turned scores of Americans into amateur criminal profilers and armchair detectives.
On Internet message boards, by office water coolers, in chats with friends, people are sharing their own theories and striking down rival possibilities.
Kathy Perkins — a church secretary in Riverside, Calif., who has been following the latest developments in the sniper attacks — believes the killer might be a deliveryman, a theory shared by others following the case.
She notes that — until this weekend — the sniper had only struck on weekdays, and police have said he could be driving a white truck or van. She believes the sniper is using a company vehicle, which he only has access to on the job.
"What if he's actually doing it at work? [That] would explain the van," she said.
But Saturday’s shooting of a 37-year-old man in Ashland, Va., could suggest the killer is adapting his methods to avoid being caught, she adds.
Lots of People With Lots of Theories
Melissa Hill, a document clerk in Minneapolis, guesses that the attacker could be ideologically motivated and trying to lash out at mainstream society.
"I think it's some sort of extremist group," she said. "I was thinking it might be a domestic one."
Hill says even though she lives far from the shootings, she finds herself discussing the case with co-workers and friends.
"It comes up somewhat often," she said. "People just talk about which theory they prefer."
Cal Nordt, who runs a small shipping company in Apex, N.C., suspects the attacks are part of some twisted game. That would explain why the crimes appear methodical but also random: The pattern is at this point known only to the killer.
"It just suddenly hit me, the guy's playing a game," Nordt said. "I thought of it as being a kind of scavenger hunt, where you have different things to check off on a piece of paper or card."
A Real-Life CSI
Robert Thompson, a professor of television and popular culture at Syracuse University, agrees that the case has grabbed the nation's attention and prompted people around the country to nurture their own pet theories.
"There are millions of people who read mysteries and watch Murder She Wrote and CSI. And what we're seeing is a real-life mystery," he said.
Some have suggested the killer could be eluding police by driving a smaller vehicle into the "white box truck" that police say may be associated with the attacks.
Several media reports have found people who think the killer is modeling his attacks after a popular video game. Some reports even refer to a sniper game called One Shot, One Kill, which, according to the editors of GamePro magazine, does not exist.
Other reports say some serial-killer buffs believe the D.C. sniper is paying homage to New York's "Son of Sam" killer, David Berkowitz, on the 25th anniversary of his attacks.
And there are more farfetched theories out there, such as the outlandish claim the government deliberately organized the sniper attacks to distract the public from the looming conflict with Iraq.
Saturday's attack, which was farther way from the earlier incidents and the first to take place on a weekend, appears to undermine at least a few amateur theories.