MONTGOMERY, Ala. (AP) — A federal judge has blocked an execution scheduled for Thursday for an Alabama inmate convicted of killing a police officer two decades ago.

U.S. District Judge W. Keith Watkins issued the stay Monday for 40-year-old Torrey Twane McNabb, one of several inmates challenging Alabama’s method of performing lethal injections.

Another Alabama inmate set to die earlier this month received a stay, and the judge says McNabb’s execution also should be delayed.

A spokesman says the state attorney general’s office will appeal.

McNabb was convicted of killing Montgomery police Officer Anderson Gordon in 1997.

Prosecutors say McNabb shot Gordon multiple times after the officer arrived at the scene of a crash that McNabb caused while fleeing a bail bondsman.

Alabama has executed two inmates so far this year.