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In the hunt for the Beltway sniper, one intriguing clue was a spent shell casing found outside the middle school. Like a spent slug, a casing can help narrow down the type of gun that may have been used. So far, ballistics tests have not pinpointed the sniper's weapon. But investigators appear particularly interested in individuals known to possess a Colt AR-15, the civilian version of the M-16 infantry rifle, or a Sturm-Ruger Mini-14 rifle. Both are semiautomatic rifles, popular with target shooters, criminals and some domestic extremist groups.
As the sniper settled into a grisly staccato of killing, he returned to gas stations and targeted less populated areas, nearer major highways: he killed his ninth victim Wednesday evening while the man was pumping gas at a Sunoco station in Prince William County, Va. And he killed his 10th the next morning, with a state trooper parked just across the way, this time in Fredericksburg, Va., about 50 miles southwest of Washington. Police blocked off I95, stopping all northbound white vans in response to a witness report. Geraldo Rivera, stuck in traffic, began broadcasting live on Fox News from his cell phone. But the shooter slipped by once again.
So the locals braced themselves for the next live report, making whatever small adjustments they could concoct. Suburban gas-station owners began turning their surveillance cameras 180°, so they pointed toward the outlying roadways and woods. And a Virginia prosecutor, lacking a suspect, talked to TV cameras about two different ways he could try to impose the death penalty on the sniper, should he ever be caught alive. --With reporting by Melissa August, Perry Bacon Jr., Eric Roston, Elaine Shannon, Karen Tumulty and Michael Weisskopf/Washington and Amanda Bower and Jodie Morse/New York