His name is Chander Matta, and police say he's a killer. But to his friends and former classmates at Arlington's Wakefield High School, he's a quiet guy they call Bobby.

Those who graduated with him from Wakefield in 1988 remember him as Bobby the gung-ho cadet in the Air Force Junior ROTC program; Bobby the offensive lineman on the football team; Bobby the somewhat insecure guy who in his senior yearbook listed "meeting new people and making money" as his goals.

Yesterday, as Matta, 21, was formally charged in Arlington General District Court with the slaying of Sherry K. Larman, word of his arrest was spreading among his disbelieving Wakefield classmates. Most of them had heard the news but hadn't realized that Chander Matta the murder suspect was the man they knew as Bobby.

"He was a really nice guy. I think everybody I knew liked him," said Erica Kan, one of Matta's former classmates. "The people he hung out with all went to college. This is just incredible."

Larman, 26, whose body was found on the top level of a parking garage in Arlington, was one of eight women identified as Washington area prostitutes who have been slain in the past 14 months.

Arlington County police say Matta also is a suspect in the death of two other prostitutes: Sandra Rene Johnson, 20, whose body was found in her South Glebe Road apartment on May 27, a day after Larman's body was found; and Jodie Phillips, 16, whose body was found in Alexandria's West End on May 30. All three victims were suffocated, authorities say.

Classmates said Matta's four years at Wakefield High were dominated by two passions: football and ROTC. He wore number 72 on the football team his senior year, and started several games. Along with some other male athletes, he coached the senior girls in their annual "powder puff" flag football game against the junior girls.

Some classmates said Matta's school days were focused on ROTC, and they said he eventually became one of the program's top officers.

After graduation, friends said, Matta, who made average grades, enrolled in a military academy in Vermont. He returned to the Washington area last summer and began taking courses in business administration at Northern Virginia Community College's Annandale campus. Officials at the college say Matta was enrolled there through this spring.

This summer, Matta was holding two part-time jobs, one as a customer services agent for USAir at National Airport, another as an employee of the Department of Defense's printing office at the Pentagon. A spokesman for USAir said Matta began work there in May; Defense officials said Matta started work at the printing office last week.

In the area around the well-kept South Oakland Street house where Matta lives with his parents and younger brother, neighbors yesterday shook their heads in amazement when asked about the activity around the Matta house over the weekend.

A man who lives across the street said undercover police officers from Arlington, Alexandria and the District surrounded the gray stone house Sunday morning, when Matta was arrested. Neighbors said that they later saw officers remove plastic bags filled with items from the house, and that authorities towed a tan car from the driveway.

The neighbors said they realized what the police were after when officers began asking them whether they had seen any unusual activity at the Matta house during the Memorial Day weekend, when all three victims are believed to have been killed.

"We were all shocked," said a neighbor who asked not to be identified. "There haven't ever been any problems over there that I know of. They all seem to be nice people, and they are avid gardeners."

No one answered the door at the Matta home yesterday. Family members would not talk to a reporter at Matta's court appearance.

"It's all just such a shock, so surprising," said Derek Morton, a classmate of Matta's at Wakefield. "Bobby was quiet, definitely not anyone who'd cause trouble. It's hard to understand it."