ATLANTA -- The Georgia Department of Corrections says a woman serving a life sentence for killing her husband and her boyfriend with antifreeze has died at the Metro State Prison in Atlanta.

Department spokeswoman Sharmelle Brooks says 42-year-old Lynn Turner was found unresponsive in her cell Monday morning and attempts to resuscitate her failed.

Brooks says the cause of Turner's death is undetermined and that the Georgia Bureau of Investigation's medical examiner is looking into it.

Turner, a former 911 operator, was sentenced to life without parole in 2007 after a jury found her guilty in the 2001 killing of her boyfriend, Randy Thompson, a Forsyth County firefighter.

Turner was already serving a life sentence for the 1995 death of her husband, Glenn Turner, a Cobb County police officer.