COLUMBUS, Ohio (AP) Ohio says a condemned killer waited too long to challenge its new and untried lethal-injection method and his execution should proceed.

The state attorney general's office says the two-drug combination has been part of the state's process since 2009 and death row inmate Dennis McGuire hasn't proved he faces a substantial risk of harm from the drugs.

State attorneys said Thursday in their filing higher courts have twice rejected arguments the drugs could cause severe pain. They say their expert is prepared to counter arguments McGuire could suffer a terrifying loss of breath.

The 53-year-old McGuire is scheduled to die Jan. 16 for the 1989 rape and fatal stabbing of Joy Stewart in Preble County in western Ohio. The 22-year-old Stewart was newly married and pregnant.

McGuire's attorneys say he was physically abused when he was younger.