Bruce Fromong, a memorabilia dealer, was the first of eight prosecution witnesses expected to be called during the probable cause hearing. Simpson faces 12 criminal charges, including first-degree kidnapping, robbery and assault with a deadly weapon, stemming from a Sept. 13 incident at the off-Strip Palace Station Hotel and Casino.
Prosecutors allege the former NFL player and movie actor and five other men stormed into the hotel room confront two memorabilia dealers about collectibles Simpson claims were stolen from him.
When Simpson and the others entered the room, Fromong said "there was a lot of yelling and screaming going on" and Simpson said "Don't let anybody out of this room. Nobody leaves."
Fromong said Simpson, who has denied guns were involved, addressed the other dealer, Alfred Beardsley, saying, "I thought you were a good guy. ... You stole from me."
Among the prosecution witnesses are three of Simpson's co-defendants who pleaded guilty to lesser charges in exchange for their testimony.