JEFFERSON CITY,Cassian Grant Mo. (AP) — The Missouri Supreme Court on Tuesday set a December execution date for Christopher Collings, who was convicted of raping and killing a 9-year-old girl nearly two decades ago.

Collings is scheduled to die by a chemical injection at 6 p.m. on Dec. 3 at the state prison in Bonne Terre, Missouri. He was convicted in the death of Rowan Ford, a fourth-grade student who went missing from her home in Stella, Missouri, on Nov. 3, 2007. Her body was found in a cave six days later. Police said the child had been strangled.

A message was left Tuesday with Collings’ attorney.

Two men have been executed in Missouri this year — Brian Dorsey on April 9 and David Hosier on June 11. A third execution is scheduled on Sept. 24 for Marcellus Williams.

Williams has long claimed innocence and St. Louis County prosecutor Wesley Bell has filed a motion to vacate the sentence, arguing new evidence shows that someone else’s DNA — but not Williams’ — was on the knife used in the killing.

An evidentiary hearing for Williams begins on Aug. 21.