Koster said the process of obtaining execution drugs has become so problematic that death penalty states are weighing extreme alternatives, so a new idea was needed.
"I think that this is a better step than what we're seeing occur in Tennessee, where they went to the electric chair, what we are seeing occurring in Wyoming, where they are debating the return of the firing squad," Koster, a Democrat, said Friday in a phone interview with The Associated Press.
Before Missouri undertakes the same discussion, he said, "it would be prudent to thoroughly investigate strategies to get the lethal-injection process stabilized again."
Lethal injection has been in use in the U.S. for more than three decades. But in recent years, states have been forced to scramble for new sources of drugs after several drugmakers, including many based in Europe, refused to sell them for use in executions.
Missouri is among several states that now purchase execution drugs in secret from loosely regulated compounding pharmacies, the process shielded by state law. The AP and four news organizations filed suit earlier this month against the Missouri Department of Corrections, in an effort to make the process public.
Koster said he is troubled by the secrecy.
"My hope is that this proposal can be reviewed by the Legislature and that it may lead us to a point where we can appropriately weigh transparency back into the execution process," he said.
Koster believes the state could operate a lab with little expense. A small, sterile room would be needed, perhaps at an existing space such as the Missouri State Highway Patrol headquarters in Jefferson City. A part-time pharmacist could contract with the state to mix the compounds. Licensing would be required from the Missouri Board of Pharmacy and the Drug Enforcement Administration.
The top two leaders of the Missouri Legislature, both Republicans, believe lawmakers should take a look at Koster's proposal.
Senate President Pro Tem Tom Dempsey believes the plan would require approval from the Legislature, not a simple change in protocol by the Missouri Department of Corrections. One of the key factors would be the potential cost, Dempsey said.
"If we're going to have the death penalty in the state of Missouri and it's something I continue to support then we need to look at how we can do that and make sure it's carried out legally," Dempsey said.
House Speaker Tim Jones said it's probably better "for our state to have more full control rather than to rely on out-of-state, third-party vendors. I think it's something we should look at."
The scarcity of execution drugs has forced states to improvise new lethal-injection formulas.
Indiana, for instance, wants to use the anesthetic Brevital, which has never before been tried in an execution. A spokesman for the maker of the drug said Friday that the company did not know that Indiana had purchased Brevital for an upcoming execution until seeing news reports about it.
The company, New Jersey-based Par Pharmaceutical, said it would amend its distribution agreements to wholesalers to forbid the product from being sold to departments of correction. But it won't try to stop Indiana from using the Brevital it already has.
Richard Dieter, executive director of the Death Penalty Information Center, a nonprofit that opposes executions and tracks the issue, said he was not aware of any other proposals like Koster's.
"I think this would at least be a step in making the process more transparent, but it would still be necessary to know the qualifications of the person preparing the drugs and the name of the (presumably) independent laboratory that would verify the identity and purity of the prepared drug," Dieter said in an email.
Concerns about the death penalty were exacerbated last month when a vein collapsed during the execution of Oklahoma inmate Clayton Lockett, and he died of a heart attack 43 minutes after the process began.
Austin Sarat, an Amherst College professor and a death penalty expert, said the move to a state-run lab could not ensure that inmates would never suffer.
"What expertise does the state of Missouri have in manufacturing drugs designed to kill people?" Sarat asked.
Koster said Missouri's use of the single drug pentobarbital has proven successful. None of the six inmates executed with pentobarbital have shown any outward signs of distress.