Robin Maher, the executive director of the Death Penalty Information Center, told the New York Times: 'This event is the worst we've seen and unlike any other botched execution in the modern era.'

Robert A. Pape, a leading authority on political violence, wants Americans to understand that the threat is coming not from the fringes, but from the mainstream.

Tennessee attempted to execute Christa Pike for a 1995 murder, but the lethal injection failed. Pike survives and was moved to a medical facility.