After hearing the testimony of 19 witnesses, seeing 100 pieces of evidence and hearing the public tarnishing of a local sports hero's name, a Prince George's Circuit Court jury is expected to begin today trying to decide who supplied the cocaine to University of Maryland basketball star Len Bias the night he died.

Sometime around noon the jury must begin sifting through mounds of paper and recalling days of testimony to answer the question that defense attorney Thomas C. Morrow said was the central issue in the case: Did Brian Lee Tribble, a 24-year-old Northeast Washington alleged drug dealer, supply the cocaine that killed Bias last June 19, or was it someone else, perhaps Bias himself?

The defense ended its presentation yesterday after three witnesses and two days of testimony. Tribble, who is facing only cocaine-related charges, did not testify in his own defense.

Prosecutors called 16 witnesses during the six-day trial, three of whom were key ones. One of them said he sold drugs for Tribble and the other two said they snorted cocaine with Bias and Tribble the night Bias died.

Tribble is charged with distributing cocaine, possessing cocaine with intent to distribute it, possessing cocaine and conspiracy to distribute cocaine. If convicted, Tribble could face a maximum sentence of 20 years in prison and a $25,000 fine.

Tribble's attorneys have tried to show that no one really knew who supplied the cocaine Bias used the night of his death in his Maryland dormitory room, and that the prosecution presented no hard evidence that Tribble distributed drugs.

But Terrence Anthony Moore, 17, a self-described cocaine dealer whose name surfaced publicly for the first time on the opening day of testimony, testified that he sometimes sold cocaine for Tribble.

The most gripping testimony came from Bias' teammates Terry Long and David Gregg, who testified that they, Bias and Tribble snorted through cut straws between one-third and one-half a cup of cocaine piled on a mirror for almost four hours before Bias fell to the floor in a seizure.

Gregg testified that he poured the cocaine from the mirror into a plastic bag and gave the bag to Tribble. Gregg said he did not know what Tribble did with the cocaine. Both players also testified that they did not know who brought the cocaine into the room.

Former Maryland basketball coach Lefty Driesell was called by the prosecution to corroborate testimony from Long and Gregg. But the coach's statements differed from their testimony on one key point: Driesell said that the two players had told him that Tribble brought the cocaine into the room.

Immediately after Driesell's testimony, Rea instructed the jury to disregard Driesell's statement about who brought the cocaine into the room, ruling that his testimony was outside the scope of what prosecutors told the defense he would likely say.

The defense yesterday asked for a mistrial on that point, but Rea denied the motion, but scolded prosecutors' handling of Driesell's testimony.

As part of their effort to portray Tribble as a major drug distributor, prosecutors alleged that Tribble used the apartment of a friend -- Julie Walker of Northeast Washington -- as a "stash house," a place other than his own residence to keep his supply of drugs.

Tribble's attorneys called Walker as their last witness yesterday. She testified that Tribble kept a safe at her Bladensburg apartment last year but that she never suspected that Tribble kept drugs in it.

Sherrie Hursey of Northeast Washington, who sometimes dates Tribble, suggested that Bias himself might have supplied the cocaine for his early-morning party to celebrate his selection in the annual college draft by the National Basketball Association's Boston Celtics.

Hursey said she was at Tribble's apartment early on June 19 when Bias arrived about 12:30 a.m., and that Bias acted anxiously when she sat on his bag. "He seemed sort of anxious to get it," she said.