KANSAS CITY, Mo. -- A Missouri man who has been in prison for more than 40 years for a triple murder many legal and political officials believe he did not commit will have to wait several more weeks before a court hearing that could lead to his release.

Kevin Strickland's chance of being released seemed to be improving earlier this week, when a judge scheduled a hearing for Thursday for prosecutors to argue he should be free. Strickland has been imprisoned since 1979.

But Missouri Attorney General Eric Schmitt's office, which has argued Strickland is guilty, filed an emergency motion Wednesday to delay the hearing to provide more time for preparation, and a Missouri Court of Appeals panel ruled in Schmitt's favor.

Instead, during a hearing Thursday, Circuit Judge Kevin Harrell set a Sept. 13 court date for attorneys to argue over motions Schmitt filed in the case. But the date for a hearing that could lead to Strickland's freedom was not set, The Kansas City Star reported.

Jackson County Prosecutor Jean Peters Baker said it was "disappointing" Strickland's innocence claim was not heard Thursday and her office is pushing for an evidentiary hearing to be set as soon as possible.

"It's just when," Peters Baker said. "While it is not yet too late, it's late. This is late."

Peters Baker announced in May she and others believe Strickland is innocent because evidence used to convict him in the Kansas City killings April 25, 1978, has been disproved or recanted.

The Star reported a year ago that two men who pleaded guilty to the killings swore Strickland was not with them and two other accomplices during the crime.

Under a new law that took effect Saturday, Peters Baker filed a motion Monday to have a hearing to allow her office and the attorney general's office to present arguments before Harrell would determine whether Strickland should be released.

During the Sept. 13 hearing, Harrell will consider Schmitt's motion the 16th Circuit Court of Jackson County and its judges will recuse themselves from Strickland's proceedings because of perceived bias in favor of Strickland's release.

One of Strickland's attorneys, Bob Hoffman, of the law firm Bryan Cave Leighton Paisner, said the delay means Strickland will miss his mother's funeral Saturday.

Peters Baker and Strickland's attorneys have argued the new law does not give the attorney general's office authority to request discovery or file motions in the case. But the appeals court Thursday rejected that argument, which will allow Schmitt to file a motion requesting discovery by this evening.

Senate Minority Leader John Rizzo, a Democrat from Independence who sponsored the new law, said the legislation was not intended to allow the attorney general's office to file motions in relation to the hearing.

The appeals court ruling sets "dangerous legal precedent" the attorney general is using to "needlessly delay justice for the wrongfully imprisoned," Rizzo said in a statement Wednesday.

The new law also could spur action in St. Louis, where Circuit Attorney Kim Gardner has said she believes Lamar Johnson has been wrongfully imprisoned for 26 years for the 1994 killing of 25-year-old Marcus Boyd in an alleged drug dispute.

The Missouri Supreme Court in March ruled against Gardner's motion for a new trial in March after Schmitt's office argued successfully that Gardner lacked authority to seek a new trial so many years after the case was adjudicated.

Gardner's spokeswoman said in a text Wednesday that Gardner "is finalizing next steps in this case and will be presenting evidence in court to deliver the justice that Lamar Johnson deserves." Spokeswoman Allison Hawk declined further comment.