ST. LOUIS (AP) — The attorney for convicted killer Roderick Nunley has filed a new appeal to the U.S. Supreme Court in an effort to halt his execution.

Nunley is scheduled to die Tuesday evening for killing 15-year-old Ann Harrison in Kansas City, Missouri, in 1989. The girl was abducted while waiting for a school bus, then raped and stabbed to death.

Defense attorney Jennifer Herndon initially appealed last week, arguing that the death penalty amounts to cruel and unusual punishment. She also has argued that a jury, not a judge, should have sentenced her client.

A new appeal, filed Monday, argues that Nunley’s constitutional rights are being violated due to the secrecy concerning Missouri’s execution drug. The state refuses to disclose who makes the drug or how it is tested.