ST. LOUIS — The Missouri Supreme Court’s decision to move ahead with two executions was questioned Thursday by some death penalty observers and opponents, in part over concern about Missouri’s proposed use of a drug that remains unproven in lethal injections and which gained infamy in the 2009 death of pop star Michael Jackson.
The state High Court on Wednesday set execution dates of Oct. 23 for Allen Nicklasson and Nov. 20 for Joseph Franklin. Both men are convicted killers.
Missouri plans to become the first-ever state to use the anesthetic propofol.
Richard Dieter, executive director of the Death Penalty Information Center in Washington, said there is particular concern about propofol because Missouri no longer requires a physician to be part of the execution team. Propofol is typically administered by a physician or nurse anesthetist under the physician’s direct supervision. If improperly administered, the inmate could suffer, experts say.
‘‘This is an experiment with a human subject,’’ Dieter said Thursday. ‘‘This will be sort of a brute force approach where you give them enough and they die.’’
Missouri Attorney General Chris Koster on Wednesday said in a statement that by setting execution dates, the state High Court ‘‘has taken an important step to see that justice is finally done for the victims and their families.’’
Jackson died from an overdose of propofol that was administered by a physician as a sleep aid.
Dr. Jonathan Groner, a professor of clinical surgery at the Ohio State University College of Medicine who has studied lethal injection extensively, said improperly administered propofol could cause suffering for the inmate.
‘‘From my own point of view a firing squad is a lot safer, a lot quicker, and a lot less painful,’’ he said.
For decades, Missouri and the nearly three dozen other states with the death penalty used a three-drug cocktail for executions. Makers of those drugs now prohibit their use in lethal injection.