An attorney for two men on Oklahoma's death row wants to introduce a firing squad as an alternative to the state's lethal injection.

Donald Grant and Gilbert Postelle are scheduled to be executed on January 27 and February 17.

Both men want to join a federal lawsuit, which challenges the state's use of a three-drug cocktail.

However, a judge said they must provide an alternative method of execution.

The judge said he hopes to have a decision by the end of the week.