There was no other motive given than retaliation for alleged domestic violence, but Dallas police have no reports on record regarding domestic violence between the couple.
Officer Larry Tuttle, a six-year police veteran, was killed Saturday inside his apartment in the 9700 block of Forest Lane, according to police.
Tuttle's girlfriend, 42-year-old Otto Machelle Thomas, called 911 and confessed to shooting him before taking her own life.
"She replied, ‘He was getting ready to hit me again and I just went off,'" said Assistant Chief Randy Blankenbaker with the Dallas Police Department. "‘I killed him because he was going to hit me again.'"
Dallas police say officers tried to prevent the woman's suicide, but were too late. SWAT officers were en route to the apartment when Thomas called 911 again.
"As officers were arriving at the scene at approximately 6:18 p.m., Ms. Thomas called 911 a second time. During this call, patrol officers can be heard repeatedly giving commands to Ms. Thomas to put the gun away and unlock the door."
Police say she left the window, telling them she was going to unlock the door when they heard a muffled gunshot.
Officers found Thomas and 40-year-old Tuttle dead inside, and Thomas' 6-year-old daughter unhurt in a bedroom.
It's unclear if the child witnessed the horrific incident.
Dallas police confirmed Tuttle is married and has a son.
Thomas was recently homeless and may have moved in with Tuttle.
FOX 4 looked into Thomas' past and did not find any prior arrests.
Her daughter is now in CPS custody, but police said that they're hoping to place the girl with family members in Mississippi.