ST. LOUIS — (AP) — A Missouri man facing the death penalty for sexually assaulting and killing a child was a frequent victim of physical and sexual abuse in his youth and has a “structurally abnormal” brain that impairs his judgment, according to a clemency petition filed on his behalf.

Christopher Collings, 49, is scheduled to die by an injection of pentobarbital Tuesday evening at the state prison in Bonne Terre. It would be the 23rd execution in the U.S. this year and the fourth in Missouri.

Collings was convicted of killing 9-year-old Rowan Ford, a fourth-grader from the tiny southwestern Missouri town of Stella, on Nov. 3, 2007. Her body was found in a sinkhole six days later. She had been strangled. Collings confessed to the crimes.

Republican Gov. Mike Parson was still weighing the clemency petition on Monday, but history is not on Collings' side: Parson, a former county sheriff, has overseen 12 executions and has never granted clemency.

Clemency appears to be the last hope for Collings. The U.S. Supreme Court on Monday rejected an appeal. Collings' attorney, Jeremy Weis, said no other court appeals are planned.

The clemency petition states that the abnormality of Collings’ brain causes him to suffer from “functional deficits in awareness, judgment and deliberation, comportment, appropriate social inhibition, and emotional regulation.” It also notes that he suffered from frequent and often violent abuse as a child.

“The result was a damaged human being with no guidance on how to grow into a functioning adult,” the petition states.

The petition also challenges the fairness of executing Collings when another man charged in the crime, Rowan's stepfather, David Spears, also confessed but was allowed to plead to lesser crimes. Spears served more than seven years in prison before his release in 2015.

Collings told authorities that he drank heavily and smoked marijuana with Spears and another man in the hours before the attack on Rowan, according to court records. Collings said he picked up the sleeping child from her bed and took her to the camper where he lived, where he assaulted her. He said he strangled the child with a rope when he realized she recognized him.

Collings told investigators that he took the girl's body to a sinkhole. He burned the rope used in the attack, along with the clothes he was wearing and his blood-stained mattress, prosecutors said.

Spears also implicated himself in the crimes, according to court documents and the clemency petition. A transcript of Spears’ statement to police, cited in the petition, said he told police that Collings handed him a cord and that he killed Rowan.

“I choke her with it. I realize she’s gone. She’s ... she’s really gone,” Spears said, according to the transcript. It was Spears who led authorities to the sinkhole where her body was found, according to court documents.

No phone listing could be found for Spears.

Like the rejected U.S. Supreme Court appeal, the clemency petition challenges the reliability of the key law enforcement witness at Collings' trial, a police chief from a neighboring town who had four AWOL convictions while serving in the Army. Failure to disclose details about that criminal history at trial violated Collings’ right to due process, Weis contends.

“His credibility was really at the heart of the entire case against Mr. Collings," Weis said in an interview.

Three men have been executed in Missouri this year — Brian Dorsey on April 9, David Hosier on June 11 and Marcellus Williams on Sept. 24. Only Alabama, with six, and Texas, with five, have performed more executions than Missouri in 2024.

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