Convicted killer Christa Pike, 50, survived two doses of lethal injection in what a death penalty expert described as the worst botched execution in modern history. Pike was administered pentobarbital at the Riverbend Maximum Security Institution in Nashville, Tennessee, on Wednesday night.

After the attempted execution, Pike remained alive and was heard snoring, leading to her being rushed to a hospital by ambulance, according to her attorneys. She remains hospitalized, but her legal team stated they have not been updated on her condition.

Robin Maher, executive director of the Death Penalty Information Center, called the event "singular and unparalleled," noting there is no precedent for an inmate surviving after receiving lethal injection drugs. Seven other individuals have previously survived execution attempts due to difficulties in accessing a vein, but not after the drugs themselves were administered.

Pike and her then-boyfriend, Tadaryl Shipp, were convicted of the 1995 murder of 19-year-old Colleen Slemmer. Pike lured Slemmer to a wooded area, where she was fatally stabbed and beaten. Shipp, who was 17 at the time of the crime, admitted to carving a pentagram into Slemmer's body. Pike was the only one sentenced to death.

This marks the second instance this year that Tennessee has been unable to carry out an execution. In May, the execution of Tony Carruthers was called off after officials were unable to establish an IV line.

Pike's execution faced legal challenges leading up to Wednesday. The 6th Circuit U.S. Court of Appeals initially issued a stay to consider allegations of childhood sexual abuse, but the Supreme Court later cleared the way for the execution to proceed. Pike's attorneys filed an emergency motion Wednesday, arguing that the prolonged suffering constituted cruel and unusual punishment. The Tennessee Department of Correction stated that its execution protocol was followed.

Pike, who was diagnosed with bipolar disorder and post-traumatic stress disorder, maintained that she was a mentally ill 18-year-old at the time of the murder and did not intend to kill Slemmer. She would have been the 30th person executed in the U.S. this year.