(Updated at 10:01 a.m., Sat., Sept. 6 with the attorney general's response)

Lawyers representing inmate Earl Ringo are asking a federal judge to halt his upcoming execution, citing new information uncovered in a St. Louis Public Radio investigation.

Earlier this week, we reported that Missouri has been using midazolam in its execution process. Midazolam, a sedative, is a controversial execution drug that has been used in three botched executions in the United States this year.

Missouri officials said previously that they would not use the drug.

"Critical state actors have perjured themselves, including the heads of the Department of Corrections and the Department of Adult Institutions," Ringo's lawyers wrote. "Lawyers for [the state] have submitted highly misleading pleadings and false claims in various courts about Missouri’s administration of executions."

Early Saturday morning, the state attorney general's office filed a response, arguing that the officials did not commit perjury.

"[Midazolam], valium and lidocaine are not used as lethal chemicals and are not part of the execution itself," Attorney General Chris Koster's office said. He argues that midazolam is part of its "pre-execution" procedure.

"Ringo has taken portions of depositions out of context and has strategically decided to classify pre-execution procedures, as in his view, part of the execution itself in order to create the appearance of contradiction. But there is no contradiction."

The state also included an affidavit of the warden at the facility where executions are conducted.

The inmate is offered Valium, which he can turn down, according to Warden Terry Russell. But Russell acknowledged that midazolam is not up to the inmate.

"The offender is subsequently evaluated by medical personnel to determine whether a sedative is warranted," Russell said. "The department currently utilizesmidazolam as this sedative."

Russell also compiled a list of when the drugs were administered, something St. Louis Public Radio has asked the Department of Corrections to turn over several times.

It shows midazolam has been administered in as few as three minutes before pentobarbital.

We have also asked the state several times to see the portion of the protocol that he says deals with sedatives. The state says it is a confidential record.

Experts we spoke with said the doses Missouri is using would do much more than "calm," as the warden said. Two experts in anesthesiology said the doses Missouri is using would likely put the inmate in a deep sleep, to the point where he would be difficult to arouse. His airway could also become obstructed at those doses.

As Ringo's lawyers point out, midazolam requires an IV.

"Establishing intravenous access is part of Missouri’s execution protocol," Ringo's lawyers wrote on Thursday."Thus, administering the midazolam is part of the execution."

Documents we obtained show Missouri has been injecting midazolam before the state's execution warrant is valid and before witnesses are present.

Ringo is scheduled to be put to death on Sept. 10 for killing two people as part of a robbery in Columbia. His lawyers are asking for a hearing and discovery on the state's use of midazolam in executions.

"The department’s actions shock the conscience, and a hearing is required to determine whether the prison intends to continue its pattern of unconstitutional executions," Ringo's lawyers write.

Read our full investigation here.

Follow Chris McDaniel on Twitter: @csmcdaniel