According to a letter from Department of Corrections Director Charles Ryan to Gov. Jan Brewer, the department no longer will use the combination of midazolam, a sedative, and hydromorphone, a pain killer. [...] the agency will try to obtain pentobarbital and sodium pentothal, the powerful but obsolete sedative that was used in most lethal injections in Arizona until it became difficult to obtain. The July 23 execution of Joseph Rudolph Wood, convicted of murdering his ex-girlfriend and her father, called into question the efficacy of the drugs used after it took nearly two hours for Wood to die. [...] results from an independent investigation conducted by a group of former corrections directors and experts found no protocols were broken, that the state properly trained its execution team, and that Wood was injected properly but did not react to the drugs as expected. "The report is clear that the execution of inmate Wood was handled in accordance with all department procedures, which, as the report states, either meet or exceed national standards," Ryan said in a statement.