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.
Cherie Freeman, a retired nurse in Tucson, Ariz., said last week she thought the number of attacks may hide a link to the al Qaeda terrorist network. At the time, the sniper had killed nine people and shot a total of 11, she noted, and last year's terror attacks are commonly referred to as "9/11."
"This guy apparently normally goes for the head," she said. "I think both of those [survivors] were intentional non-kills."
The theory, which she admitted was a little "off the wall," appears to be in trouble since now 12 victims have been officially linked to the sniper, and investigators are trying to determine if a shooting this morning in Montgomery County, Md., is tied to the sniper. A bus driver was shot on a commuter bus at about 6 a.m. ET and died in an area hospital.
Theories Swamp FBI Tip Line
The amount of amateur detective work has become a headache for the FBI.
FBI officials report that the hotline set up for tips about the case has been flooded with people offering their theories and hunches.
The agency publicly discouraged people from using the number to give their personal hypotheses about the case.
"We ask callers, however, to make sure that they provide substantive information relating to the sniper attacks; but not theories, opinion or unrelated information which needlessly tie up the tip line," the FBI said.
Instead, the FBI asked people to use the bureau Web site (www.fbi.gov) or a mailbox (P.O. Box 7875, Gaithersburg, MD 20898-7875) to send in their theories, where agents can review them at a more measured pace.
Part of the frenzy of speculation is due to the dearth of evidence made public in the case.
There is no sketch or description of a suspect, and it is unclear even if there is just one individual responsible for the attacks. Some witnesses have reported seeing two people in vans or trucks speeding away from several crime scenes.
The sniper's method of pursuing his victims is unlike most serial killers, who often kill their victims at close range, sometimes after sexually assaulting them.
Thrill Killer? Terrorist?
Many killers strike out of rage or some dark sexual impulse, but the sniper's motives are mysterious. Is he a "thrill killer," attracted by the challenge and danger of murdering innocent strangers? Is he trying to terrify the general public, or to extract revenge for some personal wrong, or a calculating terrorist part of a larger plot? Criminologists, retired law enforcement officials and other experts have suggested these and other theories.
One ABCNEWS.com message board user wonders if the location of the attacks is significant. Maybe the killer is trying to draw police resources away from the metropolitan D.C., area, as part of some grander plot, the writer suggests. The writer acknowledges the idea came from the movie Die Hard III.
Investigators themselves have shown they are open to unusual theories. The FBI is studying the pattern of the sniper's attacks on maps to try to determine if the sniper is trying to draw some kind of symbol.
Further, the public's most tantalizing clue — a tarot card with the death character — is also perhaps the most puzzling. Did he leave it to taunt police or mislead them, or was it left by someone else altogether? Does it signify an interest in the occult, or is it just a dramatic calling card chosen by whim?
And finally, the killer's ability to avoid police roadblocks and elude capture has also stirred the public imagination. Is he (or she, or they) planning his attacks carefully, or is he simply lucky?
The attention paid to profilers, who are experts trained to speculate about crimes, also increases the temptation to try it oneself.
"You can't be an amateur ballistics evidence expert," said Thompson. "You can become an amateur profiler by simply coming up with a theory."
Zodiac, JonBenét Captured Public Imagination, Too
The D.C.-area sniper case is not the first to spur the public to theorize about the attacker.
"We still get calls — almost daily — from people who believe they know who the Zodiac is," said San Francisco Police Department Inspector Kelly Carroll, referring to the so-called Zodiac Killer. The killer was responsible for at least six deaths in the San Francisco area in the late 1960s and early 1970s but he claimed in letters to police to have killed as many as 37 people.
Many people spent hours debating about the possible killer of JonBenét Ramsey, the 6-year-old girl found strangled in her Colorado home in 1996; the mysterious disappearance of former intern Chandra Levy, whose remains were found in a Washington, D.C., park; and the death of Britain's Princess Diana. The assassination of John F. Kennedy may have prompted the most armchair sleuthing.
Speculation over the current sniper has been heightened by the nonstop news coverage, says Thompson.
It may be harmful by distracting the public from other important stories, such as the possibility of war with Iraq, he says.
On the other hand, he admits, it might also aid in the capture of the killer.