The Tennessee Department of Correction is yet to say why the execution did not go as planned, though it has defended the method it used.
Dr Joel Zivot, an anaesthesiologist advising Pike’s defence team, says it was not the case that Pike had some “special immunity” but suggested it was simply that not enough of the drug pentobarbital reached her bloodstream to kill her.
Pike was injected with a second dose of the drug, according to the prison authorities’ protocol, after the first did not kill her.
In interviews with the BBC, Zivot has suggested the pentobarbital was more likely to have spread across the tissue under Pike’s skin than to have entered her bloodstream.
“Most of the pentobarbital, instead of circulating in her body, ended up in her arms, and that’s how she lived,” Zivot said.
Pike’s medical condition of thrombocytosis, a blood-clotting condition, was highlighted in advance by Pike’s legal team as an additional issue that could scupper the process. Before the attempted execution, they had filed a legal case challenging the injection protocol.
If clots of blood formed at the injection site as a result of thrombocytosis, they would potentially have blocked the chemical from entering her veins, the lawyers warned.