"Girls Gone Wild" honcho Joe Francis swears ... Steve Wynn threatened to end his life -- telling TMZ, Quincy Jones just LIED on the stand about Wynn's alleged murder plot in order to protect the casino mogul.
As we reported, Quincy testified moments ago -- insisting he never saw an email from Steve Wynn detailing a murder plot against Francis. Quincy said he never even heard Wynn threaten Francis.
But Francis believes Quincy is in Wynn's back pocket -- telling us, "[Quincy] is lying for Steve Wynn. I swear on my life, God strike me down, that I am telling the 100% truth in this matter."
He adds, "The fat lady hasn't sung yet."
Francis' lawyer is cross-examining Quincy this very moment.
As we reported, Quincy was subpoenaed to testify in Wynn's defamation suit against Francis, in which Francis has claimed Wynn threatened to have him buried in the desert over a gambling debt.