The Denver Post reported on its Web site that the witness was ordered to jail Thursday by Denver District Judge Christina Habas. The man said he feared for his life if reporters named him, and wouldn't testify even after media outlets agreed to identify him by only a first name.
Prosecutors wrapped up their case Thursday against Willie Clark, who is accused of shooting Williams after he left a Denver nightclub in 2007. Clark is a suspected gang member, and three witnesses so far have been jailed for refusing to testify against him.
Clark's defense opens Friday. He faces first-degree murder charges, and a possible life sentence if convicted.