JEFFERSON CITY, Mo. (AP) When Sheriff Rick Walter was a reserve deputy, he discovered slain college student Angela Mischelle Lawless in her idling car along a rural southeastern Missouri highway and was sure at least two people had attacked her.

He raised that and other suspicions, both during the initial investigation and after Joshua Kezer's 1994 conviction on second-degree murder in the 19-year-old woman's shooting death.

"I went as far as I could go. And it fell on deaf ears," he said. "The sheriff said, 'I have a conviction in this case, I don't even want to hear it, case closed.'"

The 48-year-old Walter never gave up searching for the truth and on Wednesday joined friends, family and defense lawyers outside the Jefferson City Correctional Center to celebrate the release of Kezer, who spent nearly half his life behind bars for the 1992 killing that a judge now says he couldn't possibly have committed.

Despite Walter's desire to take another look at the case, Kezer was wary when the lawman first visited him in prison.

"I didn't set out to free Josh," Walter said. "And I told him that at our first meeting. He was a little cold and didn't trust me."

He also met opposition from former investigators and powerful ex-Scott County Sheriff Bill Ferrell, who reminded Walter of the potential damage to his political career.

"This could have been a career-ending decision," said Walter, a Democrat first elected in 2004 in the county of about 40,000 people. "There's a lot of people who did not want me to do this. Law enforcement was my biggest stumbling block."

After all, Kenny Hulshof, a tough-on-crime special prosecutor who parlayed his credentials into six terms in Congress and the a Republican nomination for governor, was the man who convinced a jury that Kezer was guilty of shooting the Southeast Missouri State University student three times and leaving her body in her car along an Interstate 55 exit ramp just west of the Mississippi River.

Cole County Circuit Judge Richard Callahan ruled Tuesday that Kezer, who was 17 at the time of the killing, was wrongly convicted. His 44-page decision included a stinging rebuke of Hulshof, saying he withheld key evidence from defense attorneys and embellished details in his closing arguments.

Other than a statement Tuesday in which he affirmed his belief that Kezer is guilty, Hulshof has declined to comment.

The state's prosecution was based on the testimony of another suspect in Lawless' death who said he saw Kezer at a nearby convenience store on the night of the killing. But he gave conflicting testimony and three jail inmates who claimed Kezer had confessed to the killing later acknowledged lying in hopes of getting reduced sentences.

After he became sheriff, Walter assigned a team of investigators to re-examine the case and the probe turned up evidence that contributed to Kezer's release. When the 34-year-old Kezer, dressed in civilian clothes, walked out of the prison's front doors, he kept a promise to the sheriff and vigorously shook Walter's hand.

"He showed a lot of courage in coming to see me the first time," Kezer said. "He didn't know what to expect. But he still decided to look me in my eyes. He didn't play games with me. He told me was going to find out the truth.

"I told him what the truth was, but he didn't really listen to that too much. He wanted to find out what the truth was for himself."

Walter joined the department full time in 1996 and ran against Ferrell in 2000, losing by several hundred votes. He later won when Ferrell retired in 2004 after 28 years in office. Ferrell did not respond to messages left at his Sikeston home requesting an interview.

Olga Akselrod, a staff attorney with the Innocence Project, a New York-based group that works to free the wrongly accused, called Walter's work on the case, including frequently collaborating with defense attorneys, "unusual and highly commendable."

"He's a big reason why an innocent person who was still in prison all these years is now out," said Akselrod, who assisted in Kezer's defense. "The trend is clearly toward more cooperation from law enforcement."

Walter isn't done. On Thursday, he was already turning his attention to following leads he hopes will result in new charges being filed in Lawless' death.

"There's still a hole here," Walter said. "You don't want to lose sight of what started this. Somebody killed Mischelle Lawless. I will feel better when I put someone in the cell that Josh was in."

Copyright 2009 The Associated Press.