Tennessee’s prisons chief will step down following a failed attempt to execute death row inmate Christa Pike, Governor Bill Lee said on Saturday.

Pike, who was sentenced to death in 1996 for the 1995 torture and murder of 19-year-old Colleen Slemmer, remains unconscious and on a ventilator after surviving a failed lethal injection with two doses of pentobarbital on September 30, according to her lawyers.

Lee announced the resignation of Tennessee Department of Correction Commissioner Frank Strada after ordering an independent review of the botched execution.

“Commissioner Strada has served with integrity, and I appreciate his willingness to put the interests of Tennesseans first during this difficult moment,” Lee said in a statement.

“I believe this review is entirely appropriate and necessary, and I look forward to doing everything I can to help determine exactly what occurred,” Strada added.

The New York Times, citing outside medical experts, said Pike had probably survived the procedure because the lethal drug leaked into tissue around the insertion sites instead of entering her bloodstream.

Her lawyers said Pike suffered chemical burns and blisters as the execution team made at least seven attempts to insert needles while trying to find a vein suitable for administering the drug. They had previously warned that her medical history, including a blood-clotting condition, and small veins increased the risk that she would experience “unnecessary” pain.

Pike was convicted of first-degree murder after she, her boyfriend and another accomplice lured Slemmer, a fellow student, to an isolated area near the University of Tennessee agricultural campus, where Pike brutally beat her and cut her throat. Pike was 18 when she committed the crime.

The case was Tennessee’s second botched execution this year. In May, officials halted the execution of death row inmate Tony Carruthers after repeatedly failing to establish intravenous access to administer pentobarbital.

Carruthers was returned to death row, and Lee subsequently granted him a one-year reprieve. The incident had already raised questions about Tennessee’s lethal-injection procedures months before Pike’s execution.