Autopsy report doesnt explain why Oklahoma inmate writhed, took 43 minutes to die

An autopsy on an Oklahoma inmate who died after his troubled execution was halted concluded that he was killed by the lethal drugs, but it doesnt explain why he writhed, moaned and clenched his teeth before he was pronounced dead about 43 minutes after...
http://www.dailynews724.com/us/autopsy-report-doesnt-explain-why-oklahoma-inmate-writhed-took-43-minutes-to-die-h222136.html