Christa Pike‘s botched execution was a total disaster … according to the mother of the girl Christa murdered in 1995.

May Martinez — Colleen Slemmer‘s mom — told NBC Newsin a phone interview Thursday … “It was a mess.”

As you know, Christa survived 2 lethal injections Wednesday night in Tennessee during her attempted execution for Colleen’s murder.

Nashville reporter Tori Gessner described the execution during a news conference, saying she could hear Pike say … “My arm feels like it’s about to burst open.”

Christa’s lawyers described her as “still alive and snoring” after the execution had gone horrendously wrong. She was transferred to a hospital, and her lawyer says she’s “critically ill” but not comatose.

This all comes after the Supreme Court vacated her stay of execution, which had been filed just one hour before her originally scheduled execution.

Pike’s attorneys fought to get her life in prison — arguing that jurors who sentenced her to death were not presented with the full extent of her childhood sexual abuse, trauma, and mental-health history — but the Supreme Court gave the state the go-ahead to execute Pike anyway.