The media started calling him the Beltway Sniper after a cluster of killings around Washington. Then he moved 80 miles south to Virginia.
After the first eight killings, authorities expressed cold comfort in the fact that at least the shooter was sparing children. Then he shot and wounded a 13-year-old boy walking into school.
People began putting off their errands until the weekend, believing the killer to be a weekday warrior. Then he struck on a Saturday.
Slaughtering by day or night, in quick succession or after a five-day lull, targeting white, black, Hispanic or Indian, escaping perhaps in a van, perhaps in a box truck, the killer has kept police and residents guessing.
"One thing we can predict is that he's unpredictable," said Northeastern University criminology professor James Alan Fox. "In the past when we've focused on patterns, he's strived to prove them wrong."
Since Oct. 2, terrified residents in an ever-widening kill zone in the Washington-Richmond, Va., area have been running zigzag across parking lots and pumping gas behind blue tarpaulins as police look for a shadow.
"The person or people involved in this have shown a clear willingness and ability to kill people of all ages, all races, all genders, all professions, at different times, different days, different locations," Montgomery County Police Chief Charles Moose said after it appeared the sniper had claimed a 10th life.
After nine — and possibly 10 — deaths, three woundings and one miss, all anyone knows for sure is that this one-shot sniper prefers ammunition in the .22-caliber family. Commentators have taken to saying "he, she or they," since it is not even clear if it is one person or more.
Psychologists and criminologists fight over whether to call this person a serial killer or a mass murderer, while trained marksmen bristle at media accounts conferring the title "sniper" on a shooter they see as amateurish.
Newsday columnist Jimmy Breslin, who once found himself the object of correspondence from New York's "Son of Sam" killer David Berkowitz, said profiling the shooter is a pointless exercise.
"I would give death sentences to all of these television — what do you call them? — security analysts and weapons experts," he said. "They all should be incarcerated. Next thing they'll bring the psychics in."
Rockville car salesman Gary Hughes found it somewhat liberating that, short of locking himself in his house and pulling the blinds, there is nothing he can really do to stay alive.
"If you look from Spotsylvania to here, from Fairfax to Prince George's County, you've got several million people," Hughes said. "The chance of him spotting me and then picking me to shoot, you know it's one out of how many millions."
He added: "The only thing that can control how safe I am is where he is — and I can't control that."
Still, people are doing what they can do for even a little peace of mind.
Aspen Hills bus driver Albert Logan normally idles his bus by a park just off Connecticut Avenue while he prepares for his morning runs. When the shootings started, he began pulling a little farther up to get away from the tree line.
On Tuesday morning, just minutes after Logan pulled out, driver Conrad Johnson was gunned down near the very stop Logan now avoids.
"It's an eerie feeling," a shaken Logan said as he prepared for a run. "You're going to have to look out for your own self out there until the police get this guy off the street."