Report: Potential Witnesses in Mel Gibson Investigation Claim Their Lives Were Threatened

As the criminal investigation into Oksana Grigorieva's domestic abuse charges against Mel Gibson continues, The Hollywood Reporter says two potential witnesses have claimed that Grigorieva's bodyguard threatened their lives after they refused to manufacture evidence for her -- a claim an attorney for the bodyguard denies.

The possible witnesses -- Violet Kowal, a Polish porn star who claims she slept with Gibson, and her bodyguard, Nikko Riley -- told police last month that Grigorieva's bodyguard, Kristian Otto Herzog, attempted to run down Riley and verbally threatened to have them both killed, says THR.

Riley claimed Herzog told him and Kowal that if they cooperated, and said whatever Herzog wanted them to say, Grigorieva was willing to slip them some of the money she'd end up getting from her conflict with Gibson, THR reports.