Warning: This story contains graphic content.
Pike, 50, was strapped to a gurney when the curtain to the execution chamber was raised at 7.27pm on Wednesday (Tennessee time). She was allowed a final statement and said she was leaving the world with love. "I'm ready to be free," she said. "This is a happy day."
Her spiritual adviser stood beside her, stroking her forehead. They sang a song that included the repeated phrase "I love you." Minutes passed. Pike raised her head, looked around and smiled. She then told a prison official her arm was hurting and asked if it was supposed to feel that way.
At 7.37pm, ten minutes after the procedure began, she sighed. Something described as a rock or paper weight about the size of a golf ball was placed on a ledge in the control room at 7.41pm. Witnesses described hearing snoring sounds and Pike continuing to talk.
Pike was sentenced to die for torturing and murdering 19-year-old Colleen Slemmer in 1995, a crime committed when Pike was 18. She would have been the first woman executed in Tennessee in more than 200 years.
Governor Bill Lee had denied a clemency petition earlier this week, stating he was upholding the sentence. Pike's attorneys had argued that executing someone who was a teenager at the time of the offence would put Tennessee on "singular footing" in the modern death penalty era. The US Supreme Court allowed the execution to proceed after a lower court granted a temporary stay.
Wednesday's failed execution is the second in Tennessee this year. In May, officials called off the lethal injection of Tony Carruthers after failing to place an IV.
Pike's legal team had said before the execution that the governor's decision "leaves unanswered vital questions about Tennessee's execution protocol." It remains unclear what steps the state will take next.