NASHVILLE, TN (AP) - The Tennessee Supreme Court has postponed the execution of convicted murderer Billy R. Irick.

The 55-year-old has been on death row since 1986 for the rape and murder of a 7-year-old girl.

He was scheduled to die Jan. 15. But the Supreme Court this week changed the date to Oct. 7, saying there are legal challenges surrounding a drug the state now wants to use for its executions.

Tennessee announced in September that it's switching from a three-drug lethal injection method to using only the sedative pentobarbital to put an inmate to death.

Irick's attorney did not immediately return a call to The Associated Press on Thursday.

Correction Department spokeswoman Dorinda Carter didn't comment on the court's ruling, but said the state was prepared to execute Irick next month and it will be in October.

Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.