The "Route 29 stalker," suspected of killing a graduate student and dumping her body in Culpeper County, hunts for small, brunet, white women in their twenties and plans to kill again, Virginia State Police said yesterday as they released a psychological profile of the killer.

Police said the slaying of Alicia Showalter Reynolds, who fits that physical description, was committed by a man who was acting out a sexual fantasy along U.S. Route 29, where he flagged down female motorists, convinced them they had car trouble and offered them rides this year.

"I really don't think he meant to kill her," said police Special Agent Larry McCann, a behavioral scientist who worked with the FBI to create the 13-page description of the suspected killer. "He was playing out a fantasy of sexual assault that went bad. Now she's dead. . . . Once the lion tastes blood, he likes the taste. He will kill again."

No female drivers have reported accepting rides from a man fitting the alleged stalker's description since Reynolds vanished March 2 while driving along Route 29. Police said they believe Reynolds, a Johns Hopkins University pharmacology student, got into a black pickup after the driver convinced her she had car trouble. Her body was found two months later in Lignum, Va., about 15 miles from where she was last seen.

Yesterday, police described Reynolds's killer as 5 feet 10 inches to 6 feet tall and age 35 to 45, based on interviews with a half-dozen women who accepted rides and arrived safely. A white man with reddish brown hair, he probably works in a blue-collar job, police said.

Witnesses have told police the man wore a wedding ring, and he used the name Larry Breeden with at least two women, police said. They do not believe that is the killer's real name. If the suspect is married or living with a woman, their relationship is probably troubled and was especially rocky at the time of Reynolds's disappearance, police said. "This killer is your next-door neighbor," McCann said. "If you have suspicions, call police."

Police said the man tried to stop about 25 other female motorists before Reynolds's disappearance. They all closely resembled Reynolds, police said. "He knows who he wants, and that's who he goes after," McCann said. "If they don't fit the profile, he leaves them alone."

Several women reported seeing a green tarp and a toolbox in the back of the man's black truck. Some told police he became agitated, mouthed cuss words and banged his hands on the truck's steering wheel when they refused to pull over.

Virginia State Police said yesterday that they still are unsure if a Feb. 25 attack on a Prince William County woman is related to Reynolds's death. The woman, who is Latino, told police she accepted a ride on Route 234 from a man who threatened her with a screwdriver and tried to sexually assault her.

Prince William officials said they believe the incidents are linked. "It's pretty clear the cases are connected," Prince William Commonwealth's Attorney Paul B. Ebert said. "Police are keeping their avenues open, but they don't have any reason to believe anyone else" did it.

Virginia State Police said they now believe Reynolds's credit card and coat, found on Route 662 in Madison County shortly after she disappeared, were planted there by her killer to disguise his trail.

Investigators said they suspect the man has a history of nonviolent crimes and may have lived or worked in Culpeper. "It's very important to catch this guy," McCann told reporters yesterday. "Alicia Reynolds is the first homicide he's committed, but if we don't catch him, he'll kill again."

Fairfax County police said yesterday that they are investigating a similar sexual assault that occurred 3 a.m. Saturday but do not believe the incident is linked to the stalker.

The victim, a 29-year-old Alexandria woman, told police her attacker drove a yellow Honda CRX and coaxed her into pulling into a parking lot in the 7100 block of Little River Turnpike by pretending something was wrong with her car.

The suspect, described as white, about 25, with dark skin and short, curly black hair, then climbed into her car and sexually assaulted her, police said. "We're not ruling it out, but there's still nothing to connect this incident or this guy with the Route 29 stalker," Officer Onzy Elam said. Staff writer John W. Fountain contributed to this report. CAPTION: Police released this sketch in March of a possible likeness of the killer of Alicia Showalter Reynolds.