Suspects in UCI Student’s Slaying in Local Custody : Crime: Garden Grove police escort 2 teen-agers from Boston to county jails. Investigators are seeking others.

Two suspects in the slaying of UC Irvine engineering student Robert Sapinoso were in custody in Orange County on Tuesday after being transferred from Boston, where they were arrested last week in the van Sapinoso helped identify by getting the license-plate number just before he was shot.

Garden Grove police investigators escorted Vinh Quoc Ta, 18, of Santa Ana and a 17-year-old resident of Orange on separate flights Monday night. Both were booked on suspicion of murder, Ta into Orange County Jail, and the youth into Juvenile Hall, police said.

The two suspects were arrested for probation violations by Boston police last Thursday in the silver Toyota minivan authorities say was used in Sapinoso’s Aug. 17 slaying.

As authorities worked Tuesday to prepare formal murder charges for Ta’s scheduled arraignment today and a separate hearing for the unidentified juvenile, police said Tuesday that they were seeking other suspects.

“The investigation is still continuing,” said Capt. Dave Abrecht, spokesman for the Garden Grove Police Department. “We believe there were other people in the van at the time of the shooting.”

Abrecht said police think four people were in the van, but they don’t know for sure.

“It’s hard to say how many were in the van,” Abrecht said. He said police had the names of other suspects, thought to be members of a “loose,” locally based gang.

Sapinoso, a bashful computer whiz nicknamed “Zap” for his lightning-fast typing, would have been a junior at UCI this fall.

He was fatally shot in Garden Grove after jumping into his Honda sports car with a friend to chase a passing van they believed was involved in neighborhood vandalism days earlier. The two managed to get all but one digit from the license plate before someone in the van jumped out, walked up to Sapinoso’s car at a stoplight on Newland Street and opened fire, killing the 19-year-old Westminster resident.

Sapinoso’s passenger, a 20-year-old student at Cypress College from Garden Grove, was unhurt and later provided police with a detailed description of the gunman.

The passenger, who asked not to be identified by name out of fear of retribution, said Tuesday that he hopes to be called by police to try to identify the two suspects.

“You could say I’m waiting for them to call me to tell me what’s going on,” he said. “I’m just waiting for the day when I can point . . . and say, ‘That’s the guy who did it.’ ”

Garden Grove police said the van stopped by Boston police had the same license plate number and vehicle identification number as the one used in the killing. Boston police had been told to be on the lookout for the van with California registration after authorities in Garden Grove received information the suspects might be going there.

Ta and the youth were arrested on fugitive warrants from California for violating probation, but waived extradition on Friday. A third person in the van in Boston was released.

Ta was sentenced to three years’ probation June 8 after pleading guilty to charges that he burglarized a Santa Ana restaurant Feb. 1. He and three other youths, who also received probation, were caught shortly after they left the restaurant with the cash register.

Officials refused to describe the juvenile’s previous conviction in Orange County.