Columbia police are hopeful that DNA evidence and help from some college students may lead to a break in a 20-year-old murder mystery.

Carolyn Williams was stabbed to death in her Columbia home on Jan. 2, 1989. Police believe the murder was drug-related.

Tips have come in — the latest in 2005 — but none has panned out, Detective John Short said.

The case is getting new attention after students in Columbia College's Cold Case Homicide class chose to focus on it during the last semester. The elective class for students pursuing forensic science and criminal justice careers is taught by retired Columbia police Detective Mike Himmel.

The six students in the class spent 16 weeks mining hundreds of reports, eventually narrowing the suspects to six, with two considered prime suspects. They also examined and cross-referenced evidence and created a timeline of events.

DNA testing was not available to police in 1989. But investigators plan to determine which pieces of evidence to send for DNA testing by the Missouri State Highway Patrol Crime Lab in Jefferson City. Himmel said he's optimistic the tests will lead to charges.

"This is one I personally think is going to be solved," he said.

Short said having extra people with time to look through files helps investigators.

"The problem is we have regular caseload work every day," he said. "We work on cold cases when time allows, and the way business is now, time doesn't allow very much. It's nice to have a fresh set of eyes go through these cases. Sometimes, they find something we missed, and if they do, we're all for it."

One of Himmel's previous classes helped cracked a different cold case. In 2006, the class' effort helped find the remains of Mary Nobels, a Missourian missing for more than 20 years. The bones, found in a pond along a wooded area in south Pulaski County, helped incriminate Nobels' killer, John David Brown, who was already serving prison time.

The class' success hasn't gone unnoticed. Himmel said he's received a handful of requests from across the state seeking help on other unsolved cases.

"It's usually one detective working on" cold cases, Himmel said. "This gives them six more people working on it."