Placentia Woman Dies in Boston Hit-and-Run : Tragedy: Pro basketball player accused of homicide, drunk driving in deaths of the student and her friend.

An Trinh was her family’s favorite daughter, her sister says simply.

Her parents, Thang and Huan Trinh of Placentia, could depend on her to help out with anything, and she was devoted to her four siblings.

But early Friday, the 21-year-old Boston University student was struck and killed along with her best friend as they tried to cross a busy Boston street.

The driver, according to police, was Boston Celtic reserve guard Charles Smith, 23, who starred at Georgetown University and played on the 1988 Olympic basketball squad. Witnesses told police that the van hit the two young women, slowed down briefly and then continued on its way.

Police, acting on information provided by witnesses and a taxi driver who followed the vehicle, stopped the van several blocks away and arrested Smith.

Police said Smith was under the influence of alcohol.

Smith was arraigned Friday in Roxbury District Court and charged with two counts of felony vehicular homicide, driving under the influence of alcohol and leaving the scene of an accident. He pleaded innocent and was released on his own recognizance. The case was continued to May 13.

The accident occurred about 1:45 a.m. while Trinh--and fellow student Michelle Dartley, 20, of Ridgewood, N.J.--were attempting to cross Commonwealth Avenue near the campus. They had gone to get a candy bar for a friend.

In a statement released Friday, Boston University President John Silber called the accident “tragic.”

“This is not a story about the Boston Celtics or Boston University; rather, it is a story of life lost and dreams extinguished,” he said. “I can assure you that Boston University will do everything it can to help our students cope with the grief and fear these tragedies have brought down upon them.”

The news hit the Trinh family like a thunderbolt in the middle of the night, said An Trinh’s sister Thuytien Trinh, 24. “My parents are devastated; we all loved her so much.”

Thuytien Trinh said the family received a call late Thursday night from Boston’s Beth Israel Hospital, where An Trinh and Dartley had been taken after the accident.

“The doctors were taking her into surgery, so we all prayed,” Thuytien Trinh said. “I prayed that if she lived, I’d be a better person and that I’d stop doing this and that. But she didn’t.”

An Trinh had everything to live for, her sister said. Family, friends and schoolmates described her as a brilliant honors student with an inquisitive, voracious mind. She was studious, they said, but found just as much fulfillment in listening to music or walking in the rain.

She was a 1988 graduate of El Dorado High School in Placentia, where she had been an honors student and prom queen. After a brief stint at Cal State Fullerton, she transferred to Boston University, originally intending to study journalism. She soon decided that she had the capacity to become more deeply involved in helping others, and she changed her major to psychology, Thuytien Trinh said.

An Trinh’s interests and energies were boundless, according to friends. She was studying French and had recently applied for a place in Boston University’s foreign exchange program, said one of her mentors, Prof. Robert Kerr.

“She had a great passion to travel, to go everywhere and see everything,” said Kerr, an astronomy teacher who says An Trinh just happened to join his class a few semesters ago.

“Taking my class was a manifestation of her vast interest in everything that moved,” Kerr added. “I saw her last Friday when she came by to visit, and she told me she was finding her studies boring and wanted to branch out. She was one of the very best of our undergraduate population, one of the most articulate young women I’ve ever encountered.”

To her family, she remained in some respects a mystery. She was a devoted daughter but also fiercely independent, Thuytien Trinh said. To avoid asking her family for money, An Trinh worked two jobs to earn her way through school before she received a scholarship. She helped out at her aunt’s video store and worked as a lab supervisor for her father.

“At home she was very domestic and studious, but she was a different person with her friends,” Thuytien Trinh said.

With her peers she loved to laugh and dance, said Ingrid Moon, a 19-year-old student from Tustin who was Trinh’s roommate at Boston University last year.

“She had a pendulum of mood swings,” Moon said in a telephone interview from the same dorm--Shelton Hall--where An Trinh had lived. “On one extreme she could be very quiet and pensive, and at the other very jovial and quick with a joke. She loved to dance, and ‘60s and ‘70s music was her favorite. She would go out dancing with her girlfriends. She was very vibrant and full of energy.”

Moon said she was shocked to hear of her friends’ deaths but not surprised that they were together. “She and Michelle were bosom buddies; they were inseparable,” she said.

Thuytien Trinh said her brother and sisters were raised strictly with traditional Vietnamese customs. Her father is a plant controller for Hunt-Wesson Foods Inc. in Fullerton. The family had fled a teetering Saigon in 1975, when An Trinh was 5, eventually immigrating to the United States. But An Trinh was always the most adaptable and always had the most American friends, Thuytien Trinh said.

She said the family was surprised but pleased when they learned that An Trinh had become vice president of the Vietnamese student association at Boston University.

“She never got involved in anything like that at Cal State Fullerton,” Thuytien Trinh said. “We joked with her that it must be really boring out there in Boston for her to do that. We miss her so much already.”

Smith, a point guard with the Celtics, is a native of Washington, D.C., where he attended All Saints High School. He starred in basketball at Georgetown University, where he graduated in 1989. He also played for the U.S. Olympic basketball team.

The Celtics released a statement saying the team “deeply regrets the most unfortunate incident.” Celtics Senior Vice President Dave Gavitt met with Silber to discuss the tragedy and express his condolences to the families of the young women and to the college community.

Gavitt and Celtics general manager Jan Volk also spoke with Smith to convey their “emotional support in this most difficult time,” the team statement said.

“The entire team is saddened by the news and feels deep sympathy for the families of the students,” Coach Chris Ford added. “Of course, everyone on the team expresses their deep concern for Charles at this time.”

Thuytien said An Trinh’s body will be brought home for burial. Funeral arrangements are pending.