TALLAHASSEE (CBSMiami/AP) – The Florida Supreme Court has delayed an execution because of questions about a new drug being used for lethal injections.

Askari Abdullah Muhammad, formerly known as Thomas Knight, was scheduled to be executed Dec. 3. The court delayed that until at least Dec. 27 while hearings are held on a claim that the sedative midazolam hydrochloride doesn’t prevent pain after being administered to condemned inmates.

READ MORE: Miami Weather: Temps In The 30s This Weekend

Florida has used midazolam in two executions — William Happ on Oct. 15 and Darius Kimbrough Nov. 12. The state previously used pentobarbital to render prisoners unconscious before drugs that induce paralysis and cardiac arrest are administered.

The justices ordered a lower court to hold a hearing on whether the new drug effectively renders the condemned unconscious.

READ MORE: Possibility Of New Surfside Building Has Residents Worried

Knight, 62, has been on death row for nearly 40 years. He was originally condemned for the 1974 murders of Sidney and Lillian Gans of Miami Beach. He received two death sentences for their slayings.

While in prison, he was convicted of fatally stabbing Corrections Officer Richard Burke with the sharpened end of a spoon in 1980. The death warrant Gov. Rick Scott signed last month was for Burke’s murder.

On Monday, The Supreme Court said use of the drug will be the only issue to be addressed in lower court hearings to be concluded by Nov. 26. The Supreme Court will then examine the findings and has scheduled arguments in the case for Dec. 18.

MORE NEWS: South Florida Winn Dixie & Fresco y Mas Pharmacies Expect To Get N95 Masks On Friday

(TM and © Copyright 2013 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2013 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)