The David Hartless his friends and family say they know is a gentle spirit who avoids violence and whose only weapon is an acerbic wit. They remember the times he implored them to stop for injured animals alongside the road, spoke tenderly of his girlfriend and four siblings, and took pleasure in arm wrestling, art and acting.

But since Hartless, 17, was arrested a week ago and charged with murder and robbery in connection with the stabbing death of Angelica Velazco, a 20-year-old High's store clerk in Columbia, Md., some of Hartless' friends and relatives say they have been struggling to reconcile their knowledge of him with police reports depicting the Wilde Lake High School senior as a brutal killer.

"We have never seen this side of him," said Jesselyn Brown, 17, a friend who said she has known Hartless for two years and often exchanged confidences with him. "Take the most kind person you know, someone who has gone out of their way to help you, and then hear . . . something like this. It's been very hard on all of David's friends."

"Most of the time, David was a very cheerful, outgoing young man," said the mother of one of Hartless' classmates. "If somebody around here wasn't feeling so well, he'd try to say something funny and try to cheer them up. He loved to talk to people."

Behind his carefree demeanor, however, Hartless carried the scars of several painful experiences, according to his mother, who said she is "terrified" for the son who left home in August after a heated argument and who bears a striking physical similarity to her.

Hartless has been charged as an adult with first-degree murder and robbery in the stabbing death of Velazco, a cosmetologist who was working part time at the High's store near his school to finance a trip to her native Argentina.

Velazco's body was discovered in a back room by a High's customer at about 1:15 p.m. Oct. 17. She had been stabbed numerous times in the throat, arms and abdomen, and the store's cash register had been emptied. After news of the slaying spread, several customers reported having been waited on by a young man with bloodied hands.

Hartless, who is in the Howard County detention center, could not be reached for comment.

In an interview last week at her comfortable two-story house on a quiet Columbia street, Hartless' mother, Linda Rites, said she had not yet had the opportunity to talk to her son about the slaying and did not know why he was a suspect. "They say that you only know as much as you can handle," she said, her eyes filling with tears. "But as far as the brutality of this situation, I can't believe David did that."

Seated cross-legged on her living room floor, which is dominated by a wooden Buddhist shrine for practicing their religion, Linda Rites spoke of a family that has struggled to maintain a sense of stability in the midst of loss through death and divorce.

Hartless' attorney, James B. Kraft, could not be reached for comment last night on Rites' comments.

When Hartless was five years old, his stepfather from the second of his mother's four marriages hanged himself at his mother-in-law's house. "He identified with my second husband, that was the only father he knew from the time he was 18 months old," Rites said. "He used to cry, 'I want my Daddy,' but that was one thing I couldn't give him."

Two-and-a-half years ago, his maternal grandmother's strangled body was discovered in her car at a Columbia shopping center. In the wake of Hartless' arrest, police have reopened their files on the unsolved slaying, an action that Rites, who initially was considered a suspect in the 1985 case, described as "ridiculous and sick."

She added that the emotional difficulty associated with the loss of her mother was compounded for her family while she was under investigation and when an accident at work shortly after left her incapacitated for nine months. During that same period, David's sister Debbie, now 19, left home for an extended period, Rites said.

The normality that had been restored to the Rites household was disrupted again last year when Rites' fourth husband, Leo J. Rites, was arrested and charged with committing an armed robbery in Baltimore, Linda Rites said. Their marriage ended in divorce last week, four months after he began serving a 30-year sentence for armed robbery that is being appealed.

Rites said she believes that tensions over her latest divorce may have contributed to the argument that resulted in her throwing Hartless out of the house, a move she insists was meant only to give them both time "to get ourselves together." She said the youth was particularly fond of his fun-loving and attentive stepfather, Rites, almost to the point of "worshiping him," and worried what would become of him in prison.

Alec Dinwoodie, another friend from Wilde Lake who shared Hartless' passion for heavy metal music and encouraged him to try out for a part in an upcoming school play, said that Hartless spoke regularly of his difficulties at home and that conflicts between mother and son have been building for some time.

Dinwoodie said Hartless and his mother tended to argue about "the usual teen-ager-parent kind of things," but there also seemed to be a "mutual mistrust" between them.

"Suffice it to say, that with all the divorces and family tensions, he had a very messed up family history, very messed up," Dinwoodie said.

Although other friends described his home life as "strained" and "a little crazy," Rites, a psychiatric nurse who has worked at several Maryland state prisons, defended their relationship, saying it was close and full of love.

"The way this family is portrayed is that there hasn't been a lot of stability," she said. "Well, circumstances haven't lent themselves to stability. You can't control everything.

"I've said to my kids, 'I may not have raised you right, but I don't feel guilty about it because I did the best I could,' " Rites added. "I feel that a majority of our life is okay, except it has been constant tragedies. In spite of everything, I felt like we were handling it pretty good."

But if Hartless was troubled by the events around him, he did not let on, according to his friends. They said he would talk easily, though not extensively, about his past and his difficulties at home, but preferred to laugh and joke around. There were no hints of sadness in his demeanor in recent months; if anything, the reverse was true, they said.

Hartless' sister Debbie said that her brother "had really blossomed" during the last two years. Whereas he had previously been shy and had few friends, his confidence had soared as he had gained popularity with girls. When Debbie had a baby last year, her brother had become a surrogate father to his niece, something that had created a special bond between them, she said.

Jesselyn Brown said that Hartless had adjusted well to Wilde Lake High School, where he had transferred from another Howard County school last year. After making the decision not to return to his mother's house, David moved in with a classmate's family. He had worked hard to please his new family, including trying to improve his academic performance, Brown said.

Dinwoodie added that over the summer, Hartless had added 20 pounds to his tall, lanky build through weightlifting, and upon returning to school had enjoyed his new-found ability to challenge -- and beat -- some of his high school's best athletes in arm wrestling. Like other teen-agers, he entertained himself by hanging out at the Columbia Mall.

Recently, Hartless got a part as a brash young playboy in the school production of the murder mystery "Ten Little Indians," a role he threw himself into with relish, and with graduation around the corner he talked about joining the Navy to help finance his college education, Dinwoodie said.

"He seemed to have weathered his life quite well," Dinwoodie said. "There's nothing David ever said that would indicate he was capable of this kind of violence."

Kraft, Hartless' attorney, said this week that his client has maintained his innocence since his arrest. Kraft said that although Hartless has admitted being in the store about an hour before Velazco's death, he said that the teen-ager has an explanation that places him somewhere else at the time of the slaying.

During a hearing at which Hartless was denied bail last week, a prosecutor said that police have as evidence a dollar bill with a bloody fingerprint that has been linked to Hartless. Kraft said Hartless told him that he had suffered a paper cut while looking at a magazine at the High's and may have touched something while he was in the store.

Police said last week that they first began focusing their investigation on Hartless after they learned that he knew Velazco and had worked at another High's store until he was fired for tardiness during the summer. They have speculated that robbery was a motive.

Royce West, another Wilde Lake classmate, said that David had talked to him about Velazco, but it had always been in positive terms. "He said, 'I met this girl at work and she's pretty gorgeous and pretty nice.' I think he respected her because she was a manager and everything," West said.

Dinwoodie said that although he would not consider Hartless and Velazco close friends, he knew of at least one occasion when Hartless had sought her advice about a small problem he was having with his girlfriend, a high school student in Carroll County.

Both Dinwoodie and West said that although Hartless was not receiving financial support from his mother, the family he was staying with was providing for him and he did not seem overly concerned about money. Rites said that because he was a former High's employe her son knew that the company did not keep large amounts of cash in its cash registers.

Nevertheless, when her son was arrested, Rites said she begged a police officer to give Hartless a message instructing him to begin doing a Buddhist chant and praying for Velazco. Soon after, she said, she received a call from him. He was upset because he thought her instructions meant she believed he was guilty.

"I told him that wasn't it at all," she said. "I told him, 'The point is, I have to chant for Angie, everyone in this house has to chant for Angie, and mostly you, David, because you're the one who has been charged, which indicates that you have a responsibility to her, no matter what really happened.' "