SOMERVILLE, N.J. — Moments after he fatally shot a chauffeur, Jayson Williams began organizing a cover-up to make the death look like a suicide, a former acquaintance testified Monday at the former basketball star's manslaughter trial.

Dean Bumbaco told jurors Williams wiped his prints from a shotgun and then tried to place the weapon in the hands of mortally wounded driver, Costas "Gus" Christofi.

"He said, 'He killed himself. He killed himself. We all got to say he killed himself, right?'" Bumbaco testified.

One of a dozen houseguests in Williams' mansion at the time of the Feb. 14, 2002, shooting, Bumbaco is the first of the group to take the stand against him. The guests initially told police Christofi shot himself, but later some said they were coerced to do so by Williams and began cooperating with prosecutors.

Bumbaco did not witness the actual shooting in Williams' master bedroom, but described his behavior before and after the incident in largely unflattering terms. He said that at a restaurant several hours before the shooting, Williams, who stands at 6 feet 10 inches, cruelly taunted Christofi, who is 5 feet 6 inches tall.

He said Williams was telling stories and joking with a table of ex-teammates and friends when he suddenly turned on Christofi, who was sitting quietly at an adjacent table.

Williams reacts to Bumbaco's testimony about Christofi's death.

"What the f--- are you looking at? Get the f--- out of here. Are you a f---ing fed? How do I know you're not a fed?" Bumbaco quoted Williams as telling the 55-year-old Christofi.

According to Bumbaco, when Christofi started walking away, Williams said, "Sit back down. I'm just f---ing with you. Sit back down and get your shinebox, kid."

"Shinebox," he said, was a reference to a line from the mob movie "Goodfellas."

Williams, 36, who faces 55 years in prison if convicted, glared at Bumbaco throughout his daylong testimony. When Bumbaco recalled the incident in the restaurant, Williams shook his head vigorously, rocked back in his chair, and brought his fist down on the defense table.

He insists he never mistreated the driver and the shooting was an unforeseen accident — not a crime.

It was unclear how the testimony of Bumbaco, a contractor who knew Williams through a mutual friend, registered with the jury. With his colorful descriptions, Tony Soprano accent and emphatic hand gestures, Bumbaco seemed to have jurors riveted to his account of the night of the shooting.

But during a lengthy and contentious cross-examination, he lost his temper several times and gave answers that were belligerent, sarcastic and sometimes strange.

During one testy exchange with defense lawyer Billy Martin, he snapped, "I'm telling you the facts the way they took place, maybe not the way you want to spin them, but the way they took place."

At another point, Bumbaco blurted out that his and Williams' mutual friend, Kent Culuko, a key prosecution witness in the case, "might push his grandmother in front of a bus to make two bucks."

Later, asked by prosecutors to explain the remark, he said he made it "out of anger" and added that he considered Culuko a loyal friend.

"It's not a knock against Kent," he said, prompting nervous laughter from several jurors.

Bumbaco gave the jury their first inside account of the events leading up to the shooting. He, Williams and several friends attended Harlem Globetrotters basketball game at Lehigh University and then met four of the Globetrotters at a restaurant near Williams' mansion. Christofi was hired to drive the basketball players.

Bumbaco said Williams drank three-fourths of a bottle of white wine and "a couple of Johnny Walker blacks" at the restaurant. Although Bumbaco did not characterize Williams as drunk, he noted that when Williams left the restaurant, he forgot his leather coat. Jurors have already heard the coat held Williams' wallet and $2,310.

When they arrived at Williams' 40-room mansion, Christofi was reticent to enter the house, Bumbaco said. He testified that he and Culuko told the driver, a sports fan who brought a disposable camera along in hopes of getting snapshots with Williams and the Globetrotters, to come inside.

But according to Bumbaco, when Culuko asked Williams to pose for a photo for Gus, Williams instead grabbed Christofi around the neck and pretended like he was going to body slam him.

Bumbaco testified that at the time of the shooting, Williams, three of the Globetrotters and Christofi were in the master bedroom. He said that from the adjacent office, "I heard a loud boom, explosion, something."

He said that as he rushed into the bedroom, he saw Christofi's keeling over and Williams standing a few feet away.

"I kinda saw the gun falling and hitting the ground and Jayson falling to his knees and pounding the floor," Bumbaco said. "He said, 'My God, my life is over. Did I kill him? Is he dead?'"

He said no one tried to administer CPR and when someone mentioned calling 911, "Some people said maybe not, maybe we should think about it."

After wiping down the gun, Williams ordered Culuko to do the same. He said that after one guest told Williams to wash himself to remove evidence, the hoopster briefly disappeared and then returned, wet, naked and holding the Armani suit he had worn moments before.

Bumbaco said he handed the clothing to one of the guests, John Gordnick, and told him to get rid of it. Another guest is expected to testify that Williams jumped in his swimming pool in an effort to cleanse himself of evidence.

Bumbaco acknowledged that he did nothing to help.

"I felt it was a possibility that if I did anything to try to help Gus, I was putting my life in danger," he said.

He testified that 10 days after the shooting, he had a change of heart. "I just kept having these visions of Gus," Bumbaco said. "This could've been my father, my brother."

Bumbaco was the first to come forward and his is not one of the four houseguests who either cut plea deals with the prosecutor or were granted immunity for their roles in covering-up the shooting.

During friendly questioning by Lember, Bumbaco seemed uncomfortable, speaking in a soft voice, hunching over in the witness chair and peppering his answers with "kinda" and "you know."

But when Martin began his cross-examination, Bumbaco leaned back in his chair and his voice became louder and his demeanor combative.

Bumbaco defended his decision to do an interview with HBO's Real Sports, saying he felt he had to speak out after he learned that Williams and his wife were appearing on the ABC program 20/20.

"I figured someone should come on and say what actually happened," he said.

"You wanted that opportunity?" Martin asked.

"Yeah, I guess I wanted to be a celebrity," Bumbaco shot back.

The defense lawyer repeatedly challenged Bumbaco's truthfulness, pointing out that he lied under oath in his first statement to police. In that account, given the day of the shooting, Bumbaco claimed he was downstairs in Williams' home when the incident occurred.

Bumbaco acknowledged the entire statement was false.

Martin also pressed him about the seconds before the shooting. The defense maintains Williams was trying to angle the gun away from the three Globetrotters when Christofi unexpectedly entered the room and the path of the bullet.

Bumbaco contradicted that, saying the driver walked into the bedroom right behind the basketball players, but Martin noted that he never mentioned Christofi following the players in a statement after he began cooperating with authorities.

"It's not in the statement," Bumbaco admitted.

Christofi's boss, Settimio "Sam" Nenna, also testified Monday. He told jurors that Christofi was one of his best employees and recalled how excited he was to drive pro basketball players.

"He was very excited about it," Nenna said.