George Clooney launched a private investigation after receiving a
threatening phone call warning him to split from his girlfriend.

The ‘Leatherheads’ star was so shocked when he received the threatening
voicemail telling him to “dump the b***h”, a reference to his lover Sarah
Larson, he enlisted the help of his former police officer chauffeur to trace
the call to a pre-paid cell phone.

In the message, a middle-aged man can be heard saying: “Dude, your friends
asked me to give you a message - dump the b***h before you're sorry!”

George has been dating Las Vegas cocktail waitress Sarah since last year,
but the 29-year-old beauty is unconcerned by the threat.

After George played it to her for the first time, in front of New Yorker
magazine writer Ian Parker, a surprised Sarah said, “Before you're sorry?”

Sarah claims she has been the focus of many false stories involving her Las
Vegas past, adding: “They say that I'm a stripper. There's a ton of stuff
about that. I've never been a stripper. You know, just because I'm from Las
Vegas, I must be a stripper. Because I'm a cocktail server, that means I'm
an escort.”

George, 46, denied the call could be the latest in a series of pranks played
by close friends Brad Pitt and Matt Damon, insisting: “It's not a prank -
none of my friends would do that.”

After tracing the call, George and his driver attempted to discover if the
suspect had used a credit card to pay for the phone, but soon reached a dead
end in their investigation.

Sarah Larson at the Ashley Paige show at the Mercedes Benz Fashion Week Fall 2008 held at Smashbox Studios in Culver City last month.

Nice legs/butt.