Why Some Cold Cases Take Decades to Solve

Some crimes go unsolved for years — even decades. These are called "cold cases," and they leave families waiting for answers that may never come. But experts say new technology, changing relationships, and fresh looks at old evidence are helping detectives solve mysteries that once seemed impossible to crack. USA TODAY spoke with cold case experts about what finally breaks these cases open.

When a crime happens, police look for three main things: physical evidence, witnesses, and confessions. Joe Kennedy, a former police officer and founder of the Carolinas Cold Case Coalition, says those are also the main ways cold cases get solved. His group helps police departments take a fresh look at old, unsolved crimes. Kennedy says there are about 350,000 unsolved murders in the U.S. going back to 1965.

Cases go cold when those key pieces of information dry up. A witness might move away. Evidence might not be able to be tested with the tools available at the time. A suspect might stop talking to police. When leads run out and investigations slow down, a case goes cold — but that doesn't mean it's forgotten.

It might seem like time would make it harder to solve a crime. But Kennedy says time can actually be a powerful tool for investigators. Over the years, friendships fall apart, marriages end, and people who once stayed quiet may finally be ready to talk. "When we get to people in cases that are maybe 30 or 40 years old, it's just a matter of sitting down and having a conversation with them," Kennedy said.

Confessions also play a bigger role than most people expect. Many suspects struggle with guilt for years after a crime. They may have trouble sleeping, turn to alcohol or drugs, or have nightmares. "They have nightmares about having done it," Kennedy said. "Part of what happens is they end up admitting it to someone." Those admissions can happen anywhere — in a casual talk with a friend or even in a conversation at a bar.

One example is the 1994 killing of Robin Warr Lawrence, a mother found dead in her Virginia home. Police had blood evidence but no suspect for nearly 30 years. Then, in 2023, DNA evidence led investigators to a man named Stephan Smerk. Just hours after giving a DNA sample, Smerk confessed to the crime.

DNA testing has become one of the most important tools in solving cold cases. When police can't find a match in law enforcement databases, they can use a method called forensic genetic genealogy. This means using DNA from crime scenes along with family tree research to track down relatives of a suspect — and eventually identify the suspect themselves. People who use services like AncestryDNA or 23andMe can choose to share their data with public databases, which police can search under certain rules.

This technique has helped solve hundreds of cold cases across the country. But it isn't cheap. Michael Coble, a DNA expert at the University of North Texas, says forensic genealogy investigations can cost between $8,000 and $10,000. For smaller police departments that don't have much money, that price can put some cases out of reach entirely.

Money is one of the biggest reasons more cold cases don't get solved. Police departments often have to choose between everyday needs — like buying new patrol cars — and paying for expensive DNA testing. "The police chief has to decide, 'Well, do I buy a new police cruiser next year or do I do this one case?'" said Coble. On top of that, many departments don't have enough staff to assign investigators just to cold cases.

There are also rules about how police can spend their money. David Mittelman, who runs a DNA lab in Texas, says most police budgets go toward salaries and daily operations. The government pays for some types of DNA testing but not others, leaving newer and more powerful tools unfunded. To help fix this, U.S. senators have pushed for a law called the Carla Walker Act, which would send federal money to support DNA testing in cold cases.

Some law enforcement agencies are also exploring how artificial intelligence, or AI, could help solve cold cases. AI could sort through years of case files, video footage, and other records much faster than a human investigator could. Kennedy said his group is already working on building AI tools for this purpose. The technology is still being developed, but supporters believe it could uncover leads that human eyes might have missed.

Solving a cold case can mean everything to a family that has waited years for the truth. But Kennedy says the word "closure" isn't quite right. The people who were lost can never come back, and the pain doesn't fully go away. "What we may be able to do is give families some resolution, so they're not left wondering what happened," he said. For many families, that is the most important thing — finally knowing the truth after years of wondering.