Casey Anthony's Lawyer -- 911 Call Over Death Threats

The wife of Cheney Mason -- Casey Anthony's lawyer -- frantically dialed 911 last night, claiming the family has received SEVERAL death threats ... and she fears for her life.

One of the messages, according to the 911 call -- "Your scumbag husband and Baez [Casey's other attorney] better sleep with one eye open."

Law enforcement sources tell TMZ, the Masons have requested extra police presence around their Florida home.

To accommodate the family, we're told cops in Seminole County will perform multiple drive-bys daily to make sure everyone's safe.

We're told the Seminole County Sheriff's Office is also working with the State Attorney to acquire phone records to track down the callers.