The only predictable thing about the elusive sniper -- or snipers -- terrorizing the Washington area is the unpredictability of the crimes.
The 10, perhaps 11, apparently random victims were male and female; old and young; black, white, Hispanic and Asian. The shootings have occurred in the morning and at night. Four were at gas stations, but the crime scenes also have included a sidewalk bench outside a post office and strip mall parking lots.
Experts say the killer, or killers, appear to be thrill-seekers who revel in the fear they've created and the attention the crimes are receiving.
Scott Thornsley, a criminal justice scholar at Mansfield University, who specializes in serial killers, said the shooter may be planning how to increase the thrill level of his next attack. The most recent confirmed victim, Thornsley pointed out, was killed across the street from a Virginia state trooper.
"He's operating on his own timetable. He can choose the place, the time, the location, the number of witnesses," Thornsley said. "He is absolutely dictating the pace of the investigation, in a sense, by shooting so many people in a short period of time. He's driving the police crazy."
Sniper fire has cut down eight people and wounded two since the killing started the night of Oct. 2. Another attack may have occurred Monday night when a woman was shot dead outside a Home Depot store in Falls Church, Va., about 10 miles west of Washington. Police were trying to determine whether her death was related to the other sniper killings.
The absence of patterns in the spate of shootings reflect intelligence, a knowledge of how to plan and premeditate. He's not a genius, but he's no dummy, said Robert Ressler, a former FBI profiler who believes the shooter is working with a partner.
"They're smart enough to break patterns, because they know that a pattern is going to get them trapped," he said.
The shooter exclusively targeted adults with the first seven shootings. Then, after police indicated they felt schools would not be a target, shot a 13-year-old boy after he got out of his aunt's car at a school in Bowie, Md. The boy remains in critical condition eight days later.
The geography of the shootings also changed abruptly. The first five victims were gunned down in the same area of Montgomery County, Md., the sixth just over the border in the District of Columbia.
But the seventh was wounded 60 miles away, in Fredericksburg, Va. And the sniper returned to that community to kill a man at a gas station last Friday.
The sniper has left little physical evidence but may have intentionally dropped a tarot card scribbled with a taunting message to police. "I am God" was written on the card, found near where the boy was shot.
"The first or second murder, they're very paranoid, very frightened. They think the police are on to them and fear every knock on the door," Ressler said. "But when they get away with it three or four times, they develop this omnipotence. `I am walking on water,' or ... `I am God, because I've gotten away with murder."'
The longer the killer or killers remain free, the cockier they will become and the more likely to make a mistake, Ressler said.
With the more recent attacks so brazen, it may be difficult for the shooter to return to the "more safe and secure type of shootings" he has committed, Thornsley said.
"He may feel obligated to act out in a way that has not been typical of his behavior in the past," he said. "He has from the very beginning been out of character when we think of a serial killer."
Ressler believes the killer is someone who uses murder to build self-image and to satiate a need to take higher risks.
"They see no life at the end of the tunnel, because they're losers," he said. "They're probably fired from jobs. They've failed at employment, interpersonal relations, and are financially burdened. They are driven to abnormal behavior like this, because they can't cope the way normal people cope."
Ressler added that the killer, or killers, probably are thriving on the media attention.
"I think they have a true hope they will go down in the books with David Berkowitz, John Gacy and Jeffrey Dahmer," he said, referring to other well-known serial killers. "In other words, negative attention is better than no attention. I think this is what infamy is all about."