New details are emerging about a grisly murder case.

Investigators looking into the murders of Jilian Kelley, 39, and Veronica Butler, 27, whose bodies were found in a freezer in Oklahoma two weeks after they were reported missing in March, are saying they now believe the women were killed to put an end to a custody battle involving a paternal grandmother, CBS reported citing court documents.

But while the investigation continues, Kelley’s probable cause of death has been confirmed.

According to a medical examiner’s report seen by E! News, her death was due to “multiple sharp force trauma” while the manner of death was noted as homicide. Per the report, Kelley’s body had nine stab wounds and seven incised wounds, two of which “were consistent with Mrs. Kelley having attempted to defend herself.”

“Although possible stun gun marks were observed on the back on her neck and posterior left shoulder,” the report continued, “the decomposed state of her body limited definitive gross and microscopic confirmation.”

The report noted that Kelley’s injuries also involved “a devastating upper cervical spinal cord injury,” and that her death was likely “very rapid as she would have likely not only lost her ability to move her body below her head, but also her ability to breathe on her own.”

Kelley and Butler first went missing on March 30 while on their way to pick up Butler’s daughter for a birthday party after having driven from Kansas. Kelley had been with her as the appointed supervisor for the visit, according to a custody order, per search warrants obtained by CBS News.

Their car was found abandoned along a highway near the Oklahoma border where, prosecutors allege, per CBS, they were lured by suspects who had been plotting to kill them.

On April 13, investigators found the bodies of the two women in a chest freezer that had been buried in a pasture on a property rented by Tifany Adams, the grandmother of Butler’s daughter, and her boyfriend Tad Bert Cullum, according to affidavits obtained by CBS News. 

The medical examiner’s report also noted that the Oklahoma State Bureau of Investigation found “clothing, a stun gun, a role of tape, and a knife” buried below the freezer.

The owner of the property told authorities that Cullum had asked on March 28 "if he could cut a tree down, remove a stump, bury some concrete,” according to court documents obtained by CBS News, and that Cullum had carried out the project over the next day or so.

Cullum, Adams, and three other individuals—Cole Twombly, Cora Twombly, and Paul Grice—have been arrested in connection to the murders, per the Oklahoma State Bureau of Investigation.

All five suspects, per the OSBI, allegedly belonged to an anti-government group called "God's Misfits," which had a religious affiliation and convened regular meetings at the Twombly home.

Each is charged with two counts of first-degree murder, two counts of kidnapping and one count of conspiracy to commit first-degree murder, according to the OSBI. If convicted, the suspects could individually face life in prison or the death penalty in Oklahoma for the murder charges.

E! News has reached out to local police and Cullum's attorney for comment but hasn't heard back. The other four suspects are represented by Oklahoma Indigent Defense System assigned attorneys, according to the department's executive director Tim Laughlin, and "as a matter of policy, agency attorneys do not comment on pending cases in an effort to protect our clients’ privileges and interests."

For the latest breaking news updates, click here to download the E! News App