What happened in the failed execution of Christa Pike - and what next?

US convicted murderer Christa Pike is in hospital and being given "life-saving measures" after Tennessee authorities failed in their attempt to execute her by lethal injection.

The case of Pike, whose attempted execution had already been the subject of a high-profile legal battle, has raised a number of questions.

These include what went wrong, what happens next, and - for opponents of the death penalty - fresh concerns around the suffering of an inmate when an execution does not go to plan.

A review into what happened has been ordered and executions in Tennessee have been halted for the rest of the year, Governor Bill Lee said.

Pike, 50, was sentenced to death in 1996 for the murder of 19-year-old Colleen Slemmer, an attack that was perpetrated alongside her then-boyfriend Tadaryl Shipp.

She was scheduled to be put to death on Wednesday evening, local time. The injections were allowed by the US Supreme Court at the eleventh hour after the legal battle.

Pike was given two syringes of the drug pentobarbital, though her legal team said these failed to stop her heartbeat and that she could still be heard snoring.

The Tennessee Department of Correction defended the method it used, saying "the protocol does not allow for additional procedures beyond what was carried out this evening".

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