A private investigator and former Springfield alderman is appealing to Gov. Bruce Rauner in his last weeks in office about a man he believes is innocent of murder in a high-profile case from nearly 30 years ago.

Thomas McMillen of Carlinville was convicted and sentenced to life in prison for the murder of 19-year-old Melissa Koontz of Waverly in 1989.

In a Dec. 14 letter to Rauner, Bill Clutter, the founder of Investigating Innocence, asked the governor to grant executive clemency to McMillen, 68.

Clutter said two key witnesses who were never called to testify at McMillen’s trial would have contradicted key testimony provided by Donald “Goose” Johnston that McMillen abducted and stabbed Koontz, a student at Culver-Stockton College.

Johnston recanted his testimony in a 2008 video-recorded statement and signed an authorization for his release of his mental health records showing he has an IQ of 54.

Clutter, who also was an investigator with the Illinois Innocence Project at the University of Illinois Springfield, is hoping incoming Illinois attorney general Kwame Raoul and state lawmakers will look into creating a statewide conviction integrity unit.

Such units have sprung up in Texas and New York and work independently from local prosecutors, Clutter said.

Clutter also is requesting the governor ask Illinois State Police director Leo Schmitz to mobilize “an independent investigation” of McMillen’s innocence claims.

“This is one of the more compelling cases of actual innocence,” Clutter said in a phone interview from his office in Louisville, Kentucky.

Clutter has worked on other high-profile innocence cases, including former Illinois Death Row inmates Rolando Cruz and Randy Steidl.

Two witnesses who saw Koontz’s car on Waverly Blacktop Road the night of June 24, 1989, “would have made a difference in (McMillen’s) trial,” maintained Clutter.

Ann Bramblett Manning, who then lived in Waverly, was interviewed twice by Sangamon County deputies but was never called to testify. Manning’s boyfriend and driver of the car, Don Cox, was never interviewed.

In her statement to police, Manning said she saw Koontz’s car slow to a stop ahead of the couple’s car and that Cox had to maneuver around the car.

Clutter said that Manning’s story contradicted Johnston’s testimony that he and McMillen, along with Gary Edgington and Danny Pocklington, flagged down Koontz’s car. He also testified that the four had driven from the Modesto area to New Berlin and had plans to rob the first person who came along for beer and gas money.

Koontz’s body was found in a cornfield 1 1/2 miles from where she was last seen alive, leaving the Cub Foods on Veterans Parkway.

Clutter’s letter also stated that multiple witnesses who were never called to testify saw a suspicious white man lingering in the Cub Foods employee parking lot at the time Koontz was clocking out from work.

The proximity to where Koontz’s body was found is “consistent” with her being abducted from the employee parking lot, said Clutter.

Johnston also testified against Edgington, who confessed to the crime but recanted prior to his trial. Edgington received a life sentence and is being represented by the Innocence Project in New York.

McMillen has maintained his innocence. Koontz’s parents, Bob and Ann Koontz, said in a 2008 statement provided to The State Journal-Register that the evidence against McMillen was “concrete and substantial.”

McMillen’s sister, Debbie Hudson of Carlinville, also has been steadfast in believing McMillen wasn’t involved.

“He had two daughters about (Koontz’s) age,” said Hudson, in a phone interview Friday. “He’d go out of his way to help people. I believe him and I always will.”

While she wants her brother home, Hudson said she had compassion for the Koontz family.

“Nothing is going to bring her back, but imprisoning the wrong people isn’t right, either,” said Hudson. “I pray to God every night that we’ll get (my brother) home, but I also pray that they get the person (who did it).”

According to Clutter, McMillen, who is being housed at Pontiac Correctional Center, filed a post-conviction petition in 2014 and that it’s never been acted upon.

“The post-conviction process is broken,” said Clutter. “This is a remedy of last resort.”

Rauner’s last day in office is Jan. 14.

Clutter, who served one term on the city council, said there is a template for McMillen’s possible release. On his last day in office, former Missouri Gov. Eric Greitens commuted the sentence of Rodney Lincoln, who spent 36 years behind bars. Clutter and Investigating Innocence worked on Lincoln’s case.

“We hope that people who are truly objective can re-examine the (McMillen) case and make recommendations on doing the right thing,” he said.

Contact Steven Spearie: 788-1524, sspearie@sj-r.com, twitter.com/stevenspearie.