Tennessee prison chief to resign after Christa Pike's failed execution

The head of prisons in the US state of Tennessee is resigning after the failed execution of death row inmate Christa Pike on Wednesday.

Governor Bill Lee announced the change on Saturday, sharing the news in a joint statement with Tennessee Department of Correction Commissioner Frank Strada.

Strada said that his stepping down is "in the best interests" of the state, and called the ongoing investigation into the incident "entirely appropriate and necessary".

Pike, who was sentenced to death in 1996 for the murder of Colleen Slemmer, survived two injections and is now in critical condition at a Tennessee hospital as her lawyers seek to commute her sentence.

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

Lee has ordered an independent review into Pike's attempted execution and he halted all executions in the state for the year.

Attorneys for Pike called the resignation "justified" but said "it does nothing to help Christa now".

"What happened to her Wednesday reflects a systemic failure that goes far beyond any one person," Pike's legal team wrote in a statement. "We hope the Governor's call for a full, independent review will expose the profound problems within Tennessee's entire death penalty system."