The guy whose job it was to protect Oksana Grigorieva now claims he needs protection from ... Oksana's legal team, sources tell TMZ.
Sources close to Kristian Otto Herzog say ... Kristian has been getting threatening, harassing and intimidating messages from a private investigator who works for Oksana's legal team. Herzog claims the PI has been calling, texting and emailing various people, trying to dig up dirt on him.
Herzog witnessed almost everything that went on between Oksana and her lawyers.
We're told last week -- the day before Herzog was scheduled to be deposed -- he and his team were bombarded by harassing messages.
According to our sources, Herzog now has two bodyguards with him at all times and is considering moving.