FORT LAUDERDALE, Fla. -

A witness testifying in the trial of two men accused of orchestrating the killing of a prominent South Florida businessmen said one of the men threatened him while he was on the stand.

Dwayne Nicholson testified Wednesday in the trial of Anthony "Big Tony" Moscatiello and Anthony "Little Tony" Moscatiello. The two face the death penalty if convicted in the February 2001 slaying of Konstantinos "Gus" Boulis. Prosecutors say he was killed in a struggle for control of the lucrative SunCruz Casinos gambling fleet.

Nicholson was a former body guard for "Little Tony" Moscatiello. He collected the $100,000 Crime Stoppers reward for providing information that led to the arrests.

"Tony was in the business of collecting money that was owed to him [from people] who didn't want to pay him," he said.

During a sidebar conversation, Nicholson said "Little Tony" Moscatiello threatened him from across the room.

"When you all were standing up here, he was -- the first thing he said, he said I'm a rat, from there I don't know what he said," he told Judge Ilona M. Holmes, adding that Moscatiello mouthed the words "You're a piece of s***."

Holmes urged Moscatiello to control his emotions, then denied a request for a mistrial from "Big Tony" Moscatiello's attorney.

Nicholson was expected to return to the stand Thursday morning.

Earlier in the day, two police experts testified.