At Our Lady of Lourdes grammar school in Bethesda, his nickname was "Turtles." But by the time he had graduated from Our Lady of Good Counsel High School in Wheaton in 1962, William Dean Christensen, the volatile, broad-faced son of an Army intelligence officer, was known as "Mad Dogs."

Today, Christensen, 40, is a suspected serial killer.

He has been convicted of one murder in Pennsylvania, for which he is in prison. He was charged on Feb. 16 with another Pennsylvania slaying, and he has been charged in the mutilation deaths of two women in Canada. He also is being investigated in connection with at least a dozen murders of young women along the East Coast and in Canada from 1980 to 1983, according to law enforcement officials.

"We have investigations of Christensen going on along the entire East Coast, ranging from Florida to Washington," said Philadelphia homicide detective Joseph Brignola.

From the time he was first arrested at age 24, Christensen was in and out of prison, serving relatively light sentences. He would be paroled, then get in trouble again. During a recent interview, he would not answer the question of whether he had committed all the murders he is accused of.

"I've had very little time on the streets," he said. " I've been institutionalized for the last 16 years."

In fact, he has spent only nine years in prison, though he was sentenced to more than 22 years to prisons in Maryland and Canada, according to court records.

During his years in local Catholic schools, Christensen sometimes displayed a violent temper, often in response to teasing by schoolmates that got more vicious as he grew older, his former classmates said.

While on a date during the early 1960s at a Bethesda drive-in, for example, he sought revenge on a friend who had thrown a saltshaker at the windshield of his father's car by ramming the friend's car, according to several people who witnessed the incident. "He was vicious," said one. "You don't like having a saltshaker thrown at your father's car, but you don't counter by hitting another car broadside."

Christensen married in 1966 and the couple had two children. He took a job as a postal clerk, then a sales clerk, then an auto mechanic.

His wife divorced him in 1972 after he was arrested twice for assaulting her, according to court and police records. She largely has disappeared from his life. His parents, on the other hand, David H. and Genevieve Christensen of Bethesda, were charged late last year with conspiracy and harboring a fugitive in their alleged efforts to help him. Both have pleaded not guilty.

Christensen first ran into trouble with the law on his home turf 16 years ago, court records show.

The year was 1969, and Christensen, 24, picked up a 19-year-old government worker from Louisiana in a Georgetown bar. He later stabbed her 19 times. Arrested and charged with assault and battery, he pleaded not guilty by reason of insanity. But a jury convicted him of assault and battery and he was sentenced to five years in prison.

After serving six months, Christensen was paroled in August 1970, against the advice of a psychiatrist who tested him extensively.

Dr. Harold M. Boslow, director of the Patuxent Institute, wrote of Christensen in April 1970, "He is a distinct danger to society . . . a disturbed, confused individual, who has a poor masculine identification and some paranoid ideas . . . . Under stress and when threatened, this patient can become extremely dangerous."

Two years after he was released, on July 5, 1972, Christensen and a friend picked up a woman leaving Georgetown and offered her a ride home. Then, the woman later testified in court, Christensen raped her in the car as his friend drove along Montgomery County roads.

Christensen was later convicted of attempted rape by a Montgomery County jury. But the Maryland Court of Appeals overturned that conviction because prosecutors had failed to produce his accomplice as a witness.

Two months after the alleged July rape attempt, while out on $5,000 bond, Christensen and another man abducted a young woman walking home from a Georgetown bar.

According to court records, the two men drove her to Maryland and took turns sexually assaulting her in the back seat of the car. The woman told police that Christensen threatened to cut her into pieces with a hacksaw. Then they drove her to a house owned by Christensen's parents in Kensington and sexually assaulted her again.

Christensen burned her body with matches and a cigarette lighter and kept her at the house through the night, according to court papers, then released her in the District the next day.

Christensen pleaded guilty to various rape charges and was sentenced to 16 years in prison. He served seven years and eight months and was released on parole April 1, 1980.

Less than three months after he was out of prison, on June 28, Christensen was arrested for sexually assaulting a woman at a bus stop in Montgomery County. He was released on personal bond.

Then on July 18, a man fitting Christensen's description offered a Montgomery County woman a ride as she waited for a bus, then drove her to a house owned by Christensen's parents in Kensington and allegedly raped her. Based on the description she later gave police, authorities issued a warrant for Christensen, but he could not be found.

His parents said they did not know his whereabouts, but later agreed to help law enforcement officials find him, according to court documents.

On April 16, 1981, a man later identified as Christensen pleaded guilty in Montreal to raping a 21-year-old woman. The woman told police he picked her up in downtown Montreal, then drove her to a residential area and raped her. Christensen was sentenced to three concurrent 18-month sentences.

Meanwhile, Montgomery authorities learned he was in prison in Canada and filed a detainer so he would be turned over to Montgomery police when his sentence was over.

But on April 2, 1982, the Canadian authorities let him walk free, although he had served only one year of an 18-month sentence. Authorities said an "administrative error" led to his release.

Less than three weeks after that release, according to law enforcement authorities, Christensen began a 21-month killing spree. He drifted through Canada, Pennsylvania, Maryland, New Jersey, New York, Kentucky, Georgia and Florida, according to police in those states, using a series of aliases and altering his hair style, facial hair and eyeglass frames.

Early in the morning of Sept. 23, a 23-year-old go-go dancer named Michele Angiers was stabbed to death outside her apartment over a bar in Dickson City, a small working-class community of 5,000 in northeast Pennsylvania.

Angiers, who danced under the stage name of "Sister Sarah" at the Oz Bar in nearby Scranton, was stabbed 30 times in the upper and lower back, with some wounds measuring as deep as 6 inches.

On top of her blood-drained body, police found a yellow and orange stuffed Pac-Man toy, allegedly bought for her the night before by a lumbering man with a pockmarked face who, witnesses said, picked her up at the bar where she danced.

That man, known around Dickson City as Stanley Holl, later was identified through fingerprints by authorities as Christensen.

Police found him on Dec. 4, 1983, sitting in a Philadelphia bar, eating a club sandwich and sipping a beer. Only minutes before, he had shot to death 51-year-old Joseph Connelly outside another bar. He will be sentenced to mandatory life in that murder this spring.

"How could he have been free all this time?" asked Jack McMahon, the assistant district attorney in Philadelphia who successfully prosecuted Christensen -- known as "Jeffrey Shrader" -- for Connelly's murder. "Mr. Connelly would be alive today if those things hadn't occurred. Every time there was a little crack, Jeffrey, or Christensen, slipped through, and as a result a lot of people are dead," McMahon said.

Ten days after a Philadelphia jury convicted "Jeffrey Shrader" of the Connelly murder, Montgomery investigators said they followed the lead of an address found in his parents' garbage in Bethesda and alerted Philadelphia homicide detectives that Shrader was Christensen.

The Philadelphia detectives then searched a run-down row house where Christensen lived. He had moved into the house after his mother, using her maiden name of Brogan, bought it with $10,000 cash in September 1983, according to police. The police found a hacksaw stained with human blood and clogged with human tissue. They also found a clear plastic bag stuffed with hanks of reddish-blond hair.

Those findings linked Christensen to mutilation slayings of two women in Canada. Canadian authorities issued fugitive warrants on Christensen for those two slayings.

Christensen's parents, who live at 4309 East West Hwy., face charges of sending their son money and buying the Philadelphia row house. The elder Christensen is 78, his wife, 77.

The two sat stoically last December at a hearing before District Court Judge Edwin Collier, bundled in overcoats in a chilly courtroom. FBI agents and police detectives from Philadelphia and Montgomery County paraded before them, testifying about the crimes of their son. At one point, Genevieve Christensen reached over to her husband of 54 years to help him split in half a nitroglycerin pill to quell his racing heart.

"They're cooking up a lot of murder charges ," David Christensen later told a reporter. "They can cook them up anywhere they want -- Montana, Alabama, anywhere -- I'm not going to talk about it."

The courtrooms of Montgomery County are far removed from the world where David and Genevieve Christensen grew up. While he was studying law at Harvard, David, a Mormon from Utah, met and married Genevieve, the Irish Catholic daughter of a Boston city councilman and friend of the Kennedy family.

By the end of World War II, the elder Christensen was the head of the Army's Criminal Investigation Division, a unit that investigates major crimes by and against military personnel. He later served as an intelligence official. The couple had three children: a daughter, an older son who died at 23 of cancer, and William, according to Victor Crawford, a Rockville lawyer who has represented the Christensen family since the early 1970s.

That son's death "focused all their love on" William, Crawford said. "He was the survivor and they became terribly overprotective, especially the mother."

John Clemens, a 41-year-old national salesman for Yellow Pages who went to school with William Christensen, remembers that overprotectiveness.

"At Good Counsel, if it was a rainy day, Bill would be the only kid wearing those big galoshes," Clemens said. "And while the rest of the kids carried their books in a backpack or a scruffy old duffel bag, he carried his in an old leather briefcase of his father's."

It was Valentine's Day in Holmesburg Prison in Philadelphia, and Christensen was giving a rare interview, his 6-foot-1 frame, weighing more than 200 pounds, slumped into a metal chair.

The half-smile his former classmates remembered surfaced occasionally, only to give way to sudden flashes of anger. He insisted on directing the interview, peppering his talk with obscenities derogatory to women. Yet he insisted, "I love women, I am attracted to women . . . . "

He spoke of psychological problems and an alcohol dependence that triggered different personalities.

"I have a thing where I'm insane, but it's latent," he said. "Alcohol can trigger it."

Christensen bristled when the case against his parents was mentioned: "I feel extremely upset that they would harass . . . my parents. Because I love them so much, I stay away from them, because I don't want to be a lightning rod for all this trouble. I guess I haven't done a very good job."

The interview was nearly over. Christensen had opened up, was looser than in the early part of the hour. The last question, once again: Is he the serial killer that law enforcement officials say he is?

"I've been zapped out and drunk a lot of times. How can you say what you do when you're zapped out and drunk?" Christensen said, his blue eyes darting beneath lashless lids.

Shortly after the interview, Christensen picked a fight with a fellow inmate and brutally beat him, prison authorities said.