And with the help of Dr. John Bond, a scientist from England who has invented a technique for fingerprint detection, Walter and his lead investigator, detective Branden Caid, have found even more incentive not to quit.
Bond is able to find fingerprints from metal surfaces, Walter said, by analyzing the corrosion to the metal caused by fingerprint sweat.
He applies an electric charge to the object, which he firsts covers in a fine conducting powder. Recently, Bond, whose technique was named one of Time Magazine's top 50 inventions in 2008, discovered a print on a piece of evidence sent to him by Walter and Caid.
Although Bond's technique is typically used on shell casings, Walter declined to comment on what piece of evidence from the case Bond studied.
"We sent this to him with the understanding that he gave us less than a 5 percent chance that he would find something. [Bond] said that had this been a year before, he would give us less than a 1 percent chance," Walter said.
Walter reopened the Lawless murder case in 2006, after suspicions arose that the wrong man was convicted. Joshua Kezer, a native of Illinois and a teenager at the time of his incarceration in 1994, was the defendant convicted and given a 60-year sentence for the murder of Lawless.
After a 2009 hearing before Richard Callahan, Cole County circuit judge at the time, Kezer was exonerated. Callahan's ruling examined key evidence in the case that was kept from Kezer's attorneys during his trial.
As 2010 comes to a close, Walter said he still has a few suspects he is confident about.
"I would have liked an arrest by the end of the year. I don't want to rush or push anything until I have more," he said. "With this evidence, this may give me a stronger case."
National coverage on the CBS "48 Hours Mystery" program gave the case a boost in March, and a short time later the show "On the Case with Paula Zahn" on the Investigation Discovery Channel aired a feature on the Lawless murder.
Without the coverage, Caid said, the department may not have discovered Bond's invention. A Syracuse, N.Y., man, he said, saw the show in March and called the Scott County detectives handling the case, informing them of Bond, whose technique he first saw on "America's Most Wanted."
According to a report from the University of Leicester in the United Kingdom, Bond's fingerprint technology has been used in up to 100 murder cases around the globe.
"It was very helpful to get that information," Caid said. "It all fell into place. ... We're very lucky everything worked out the way that it did."
Before the "48 Hours Mystery" broadcast ended and in the days following the show, phone calls and e-mails poured into the sheriff's department. Although many of the calls were from people who wanted to share their theories on the case, Walter said it helped him and Caid develop some leads and encouraged them to set up interviews. The "48 Hours" broadcast will run again Jan. 1.
"We did get some good information we were able to follow up on. It did really help us," Walter said.
While they continue to look into leads, Caid said they're seeking out the next step, such as finding a forensic photographer to photograph the print Bond developed off the evidence. If a photographer can get good photographs, the department hopes they can send the pictures to a lab and possibly get the fingerprints entered into the FBI's Integrated Automated Fingerprint Identification Database and find a match.
"Hopefully we can provide some rock solid evidence [a jury] wouldn't have to ponder over too much," Caid said.
If there's no match and the process leads to a dead end, investigators will go back and interview suspects again.
"I believe they may be withholding some valuable information," Walter said. "I think we'll get to the bottom of it. Knowing and proving is two different things, obviously, but I think we will find out who did this."