Arizona Dad Who Left Toddler Daughter to Die in Hot Car Dies Before Sentencing

An Arizona man who pled guilty to the murder of his 2-year-old daughter died the night before he was set to turn himself in to authorities ahead of sentencing ... TMZ has learned.

Christopher Scholtes' November 4 death is being investigated as a suicide, the Maricopa County Medical Examiner in Phoenix confirms to TMZ.

Law enforcement sources tell TMZ ... authorities are looking at carbon monoxide poisoning as a possible cause of death ... but the Maricopa County Medical Examiner will make the final determination. According to the Pima County Attorney's Office in Tucson, he died Tuesday night.

Scholtes left his toddler daughter, Parker, asleep in his car in July last year and went into his house in Marana, a suburb of Tucson. He reportedly played video games and watched porn inside, according to the Arizona Daily Star.

The temperature that day, July 9, reached 109 degrees, and the little girl had been left in the car for about 3 hours, according to the Pima County Attorney's Office. Paramedics responded and took the child to a hospital, where she was pronounced dead ... her body temperature had reportedly reached 108.9 degrees.

Scholtes pleaded guilty to second-degree murder and child abuse two weeks ago in a plea deal that would have him serve no more than 30 years for both counts. He was set to surrender to authorities today ahead of his sentencing on November 21.

Another of his daughters, who will turn 18 this month, sued him for emotional distress last month, according to Tucson's KVOA-TV.