Police Investigate 3 Men Held in Catering Truck Killings : Crime: The suspects must be charged today or freed. Detectives check whether others might be involved.

Los Angeles police said an investigation of three men arrested in the slayings of five North Hollywood catering truck employees was continuing Wednesday as detectives also attempted to determine if others were involved in the slayings.

Police have remained unusually tight-lipped about the Tuesday morning arrests of Tony Rivera III, 32, and Edward M. Taffolla, 24, both of Los Angeles, and Lawrence Aquinaga, 26, of Santa Maria. The men must be formally charged today in the December slayings of the caterers or be freed. Police said they would not discuss the case at length until charges are filed.

“It was an unusual case to start with,” said Capt. William Gartland, head of the robbery-homicide division. “We are not sure we have all the suspects in custody, and we have more investigative leads to follow.”

The arrests come as part of an investigation launched Dec. 10 when the bound bodies of the five catering truck workers were discovered near a guardrail in remote La Tuna Canyon in the San Fernando Valley.

The victims were the truck’s owner, Ismael Cervantes, 43, of Sylmar; his son, Ismael Cervantes Jr., 13, of North Hollywood; brothers Heriberto and Jesus Sandoval, 16 and 19, and Francisco Gasca, 31, all of North Hollywood. Gasca was the cook on the truck, with Tacos Tortas painted on its side, while the Sandoval brothers did odd jobs. The younger Cervantes, a Little League baseball standout, worked with his father on weekends to earn extra money.

Four of the victims had been shot and stabbed, but Heriberto Sandoval had been beaten and stabbed. Two days before the bodies were discovered, the catering truck they worked on was found ransacked and abandoned in North Hollywood. It had last been seen in operation on Saturday night, Dec. 7, parked on Lankershim Boulevard near Vanowen Street--a spot where it had been an almost nightly mainstay for several years.

Police refused to reveal the motivation behind the killings.

A spokesman for local catering truck operators, who began meeting with police to discuss safety concerns after the killings, said the three suspects were not familiar to members of his organization.

Santa Maria police officials said that department had nothing to do with the investigation and that Aquinaga, the local suspect, was not familiar to them. A state Department of Corrections spokeswoman said a computer check showed that none of the three men had served time in state prisons.

The three were being held without bail at the Parker Center jail.