TULSA, Oklahoma - Amber Hilberling was three years into a 25-year prison sentence for the 2011 murder of her husband Josh when she was found hanging dead in her cell in October.

The medical examiner ruled her death a suicide, but Hilberling's family wants a separate investigation.

The autopsy states Hilberling had an electrical cord around her neck and had meth in her system. Her prison records show she had previously tested positive for meth and marijuana during her time in prison.

Hilberling's mother had just posted a photo of her daughter on Facebook Sunday, saying how much she was missing her. 

Rhonda  Whitlock and her husband were interviewed on the Dr. Phil show after Hilberling's death and told him they didn't believe Amber took her own life.

"She was depressed, not suicidal," Whitlock had said on the Dr. Phil show.

They've hired a law firm to investigate Hilberling's death. That firm sent the News On 6 a statement, that says in part, "...While the circumstances surrounding Amber's death remain unclear, the prevalence of contraband inside correctional facilities is often associated with funding deficiencies imposed by the Legislature. Amber was cherished by her family, they are devastated by the loss, and they will continue the investigation for answers... regarding factors that caused or contributed to her death."

The case got national attention when Hilberling was arrested and later convicted of pushing her husband Josh to his death through a 25th-floor window in downtown Tulsa.

The autopsy noted Hilberling had scars on her wrist. Her former attorney, Jasen Elias, told News On 6, "Amber was the prison's most famous inmate, which made her life inside a daily hell. It's not a shock that on occasion she tried to feel an escape from what had become unbearable pain."

The Department of Corrections said it could not comment on anything regarding Hilberling's health while she was in prison because it would violate privacy laws.