Tennessee has halted its remaining executions for the year. The decision came after Christa Gail Pike survived a lethal injection on September 30.

Officials administered two doses of pentobarbital. Pike, 50, remained alive. She was taken by ambulance to a hospital. A death penalty expert called it an unprecedented failure.

Pike was sentenced to death for a 1995 murder she committed at age 18. She would have been the first woman executed in Tennessee in more than 200 years.

An appeals court stopped the execution an hour before it was to start. The US Supreme Court later overturned that stay. The execution then proceeded and failed.

Governor Bill Lee ordered a comprehensive third-party review. “The people of Tennessee expect it to be done in a manner that is not only legal and constitutional, but is effective,” he said.

The state’s protocol calls for a second set of drug syringes if the inmate is not deceased after the first. It does not say what happens if the inmate survives the second set.

The Tennessee Department of Correction said it followed every step of the established protocol. Pike’s attorneys said they were not told about her condition.