Updated

Louisiana is postponing an execution for at least 90 days after the state abruptly changed its lethal injection protocol last week.

The state corrections department said Monday that it agreed to the delay for Christopher Sepulvado, who killed his 6-year-old stepson two decades ago.

The state had trouble purchasing the drug that it said would be used for Sepulvado's injection. So, the corrections department announced last week it was altering its execution plans to a two-drug combination used in Ohio.

Sepulvado's lawyers wanted more time to study the new execution plans and determine whether the switch could violate Sepulvado's constitutional right against cruel and unusual punishment.

A federal judge will hold a trial about the constitutionality of the new execution protocol on April 7.