OKLAHOMA CITY - Court documents reveal why prosecutors are seeking the death penalty for a former Marine charged with six counts of murder.

We first told you about the shooting deaths of four people and two unborn babies back in 2009. Police found their bodies inside a burning house.

Flames masked the murders when firefighters arrived to the home in southwest Oklahoma City in November 2009.

When police made it inside the house, they found three women and one man shot to death. Two of the victims were pregnant.

Prosecutors charged David Tyner with six counts of murder for shooting, stabbing and then burning the body of a reality star from HBO's Cathouse series, Brooke Phillips, and her friends Jennifer Ermey, Milagrous Barrera, Casey Barrientos and two unborn babies.

The documents indicate the murders of all four victims were especially heinous, atrocious, and cruel. Prosecutors note the victims were shot in either their hands or legs to "partially immobilize them" leaving a "feeling of total vulnerability in the victim."

The report shows Phillips was shot in the leg in a separate room of the house and "would have heard gunshots and cries of pain from her friends… knowing she was next."

Prosecutors suggest testimony will reveal Tyner's plan was "to kill first. and then take the money" from his roommate Casey Barrientos. The report states evidence will prove " the murder of Casey was "motivated by money, drugs and Tyner's perception of Casey being disrespectful."

The document also reveals a witness is set to testify Tyner waited for Casey to get home despite two people in the home and two others stopping by the home. Tyner "followed through with his plan and eliminated all of his witnesses" by shooting them multiple times in the back or killing them "execution style" as each person listened to the murders.