OKSANA GRIGORIEVA has been left "scared to death" by threatening phone calls.

The Russian singer - who is at the centre of domestic violence allegations against her former partner Mel Gibson - is frightened for her safety after receiving "multiple" telephone messages abusing her for making domestic violence allegations against the 'Braveheart' star.

A source told gossip website TMZ that at least one of the calls "could be interpreted as a death threat".

Meanwhile, police reportedly want to interview Oksana's 12-year-old son Alexander - whose father is former James Bond actor Timothy Dalton - as they believe he is "a very important percipient witness" to the former couple's volatile relationship.

The youngster lived with Mel and Oksana - who have an eight-month-old daughter, Lucia, together - and the Los Angeles County Sheriff's Department believe he may have witnessed the aftermath of the couple's row when the actor allegedly knocked out his former lover's teeth, though he is not thought to have seen the attack.

Oksana is not expected to block investigators from interviewing her son.

Last night (13.07.10), a third tape featuring Mel's rants against Oksana was released, in which he brands the singer a "mentally depraved idiot".

He can be heard shouting: "You're a f***ing mentally deprived idiot. You're a f***ing using w***e. I own you. You don't count."

The 54-year-old star also brands a Latino employee a "wetback" as the couple argue about the unnamed staff member working at both their houses when Mel insists she can only be at his.

He says: "I will fire (name omitted) if she's at your house. I will make it known and fire her. I'll report her to the f***ing people that take f***ing money from the wetbacks, OK?"