Chander Matta, charged with slaying one prostitute and suspected of killing two others in Arlington on Memorial Day weekend, may have "snapped" after breaking up with a girlfriend and having problems in school, law enforcement sources said yesterday.

Police also are looking into why Matta's bank account grew by about $2,000 just after the women died. The prostitutes had no money on them when their bodies were discovered, the sources said.

And police sources said they are looking into whether Matta may have been involved in the death of a fourth prostitute, Carolen Marie Wallace, 22, of Forestville, whose body was found Feb. 14 stuffed in a storm sewer along Interstate 95 near Telegraph Road. She had been shot once in the head.

D.C. police say they do not believe Matta is involved in the killings of four other District prostitutes since April 1989.

On Sunday, Matta, 21, was charged in the death of Sherry K. Larman. According to police, he also made statements in a tape-recorded interview leading them to believe he killed Jodie Marie Phillips and Sandra Rene Johnson.

"You're talking about {killing} three women in a short period of time," said one source familiar with the investigation. "We've had a hard time figuring this guy out. I think there was a lot of pressure . . . . "

One source of stress on Matta may have been an "on-again, off-again" relationship during the past two months with a girlfriend, the sources said.

Most recently the relationship was "off," they said.

The girlfriend looks "a lot like the prostitutes," according to police sources. They would not identify her.

The slain women were white, slender and had light-colored hair.

Police sources also said that Matta had experienced academic difficulties. He graduated from Wakefield High School in 1988 with what have been described as average grades. He subsequently enrolled in a military academy in Vermont, where he had a D average, police sources said.

Last summer he returned to the Washington area and began to take business administration courses at the Annandale campus of Northern Virginia Community College, where he remained through this spring.

On April 26, Matta was accepted at Old Dominion University in Norfolk for the fall semester. The school's financial aid office declined yesterday to say whether Matta had sought financial assistance to attend the Tidewater school.

"He put pressure on himself to do well in school and he wanted to put himself through school," said one of the sources, who asked not to be named.

Arthur Reynolds Jr., Matta's attorney, said yesterday that prosecutors had discussed with him the possibility that his client had problems with a girlfriend and troubles in school. He would not give details of those discussions.

Reynolds declined to comment on the money added to Matta's bank account. He also would not comment on whether he will request a pyschiatric evaluation of his client, which might be a prelude to an insanity defense.

Matta's parents are "at a loss" to understand how their son, described by friends as quiet and friendly, could be facing such charges, Reynolds said.

Arlington police and prosecutors would not comment on Matta's relationship with his former girlfriend or on the money added to his bank account. Deputy Commonwealth Attorney Arthur Karp confirmed that Matta had academic problems.

Larman, 26, was found May 26 on the top level of a parking garage in the 900 block of South Highland Street in Arlington, with a plastic bag over her head. Johnson, 20, was found in her apartment at the Country Club Towers, 2400 S. Glebe Road in Arlington, on May 27. Phillips, 16, was found May 30 near a west Alexandria office complex, with the plastic bag still bunched around her neck. Police said she had been dead for three or four days.

The Phillips case provided police the break they had been searching for. In the bag around the teenager's neck, Alexandria police found a credit card receipt, bearing the name of Matta's father.

Police believe Phillips and Larman were killed in the basement of the home of Matta's parents in the 1800 block of South Oakland Street in Arlington.

All three women had worked in an area where prostitutes congregate in downtown Washington known as "the stroll," on L Street between 12th and 15th streets NW.

Staff writer Stephanie Griffith contributed to this story.