What is the oldest cold case ever solved?

From practically the very beginning of the investigation, a young man named John Tessier was near the top of the suspect list. A neighbor of the Ridulph family, he was the oldest of seven children, and community members described as being "unstable" and "creepy." The fact that he matched Sigman's physical description of the kidnapper didn't help his chances either [source: Callahan].

What he did have, however, was a seemingly solid alibi. Although it looks pretty questionable in hindsight, his parents offered up not one, but two. First, his mother claimed that he was home all night long. Except for when she asserted that he had been 40 miles (64 kilometers) away in Rockford, Illinois, enlisting in the United States Air Force. Investigators found a collect call had been placed from Rockford to the Tessier home by John Tessier at 6:57 p.m. Two Air Force recruiters verified he had shown up at the recruiting station (which had closed) between 7:15 and 7:30 p.m., and they told him to come back in the morning. Tessier was essentially let off the hook. He left Sycamore immediately [source: O'Neill].

But in 1993, Tessier's heretofore-devoted mother Eileen gave a deathbed confession to her daughter Janet, naming John as the killer of Maria Ridulph. "You have to tell someone," insisted Eileen [source: Callahan]. Janet reached out to law enforcement several times over the years with no results. Finally, in 2008 she sent an email that struck a chord with a police commander, and the case was reopened [source: Callahan].

The new investigators noticed that they only had the kidnapper's word for it that the kidnapping happened around 7 p.m. (Sigman had asked him what time it was before she went to fetch her mittens.) What if in fact the abduction had happened closer to 6? Tessier could have had time to take Ridulph and still make it to the recruiting station 40 miles away. Studying past interviews with witnesses supported the earlier timeline. In 2010, Kathy Sigman was brought in to see if she could ID Tessier from a lineup [source: O'Neill].

On Dec. 10, 2012, 73-year-old Jack McCullough (formerly John Tessier) was sentenced to life in prison for Ridulph's murder. Prosecutors said he dragged Ridulph into an alley, choked her with a wire and stabbed her before disposing of her body miles away [source: Newcomb].

Although no physical evidence was available to contribute to the conviction, the prosecutors convinced a judge of his guilt, using Sigman's photo lineup identification, several testimonies from jailhouse informants alleging that he'd confessed to them separately and a history of sexual deviance. (Tessier waived his right to a jury). Earlier, Tessier had pled down a statutory rape charge to avoid prison. He also had a history of offering and giving piggyback rides to other young girls in the neighborhood before Ridulph's disappearance [sources: Callahan, O'Neill].

There was no damning DNA evidence to put the nail in the coffin of this case, a lack of which has drawn the ire of McCullough, some of his family and some legal experts.

McCullough insists that he's innocent of the crime, and certain members of his family and his defense attorney back him up. Among the alleged holes in the case is a lack of forensic evidence tying him to the crime. Ridulph's doll, which was handled by the killer and recovered hours after the search for the child began, has long since been lost, taking with it the potential for any DNA or fingerprint evidence. His mother's confession has also been called into question, and is impossible to verify since she is long since deceased. The defense also claims that his sister Janet's apparent hatred for Tessier is motive for her to want to see him behind bars. McCullough insists that the photo lineup given to Kathy Sigman was intentionally skewed to get her to select his image over the other men shown, since their pictures were all relatively similar in appearance and his was somewhat different. Some experts also point to the fallibility of eyewitness testimony and jailhouse informants, who often are looking for some type of leniency in exchange for cooperation [sources: O'Neill, Goode].

Although many crime procedural shows (and apparently McCullough's defense) would have us believe that DNA and forensic evidence are the most common catalysts for cold case convictions, at least one scientific study shows otherwise. Published in the Journal of Forensic Sciences in 2014, the study found that, of the cold cases researchers examined, a mere 3 percent of cases were solved using DNA or other forensic evidence, as compared with 63 percent of cases involving testimony of new witnesses [sources: Vergano, Davis et al..]. In this case, Tessier/McCullough's mother provided new witness information that changed the scope of the original investigation, and the prosecution gathered enough other evidence to adequately prove his guilt, at least in the opinion of the presiding judge.

Plus, it's not exactly new territory for an accused/convicted criminal to claim they're being wrongfully targeted. Just ask anyone who believed serial killer Ted Bundy when he maintained his innocence, only for him to eventually confess to at least 30 murders [sources: Pinsky, Bergeron].