CHICAGO (CBS) — Murders in Chicago were down last year, but it’s a different story when it comes to the number of murders actually solved.

As WBBM Newsradio’s Steve Miller reports, the murder clearance rate – the number of homicides that were solved the same year – has slipped.

READ MORE: IDES Kept Offices Closed While Many Struggled To Get Their Unemployment Benefits: What Really Happened

LISTEN: WBBM Newsradio’s Steve Miller reports

“Forensic evidence may need processing time… so it stands to reason that an investigation may extend beyond a calendar year,” a police spokeswoman said.

But in 1991, for example, the murder clearance rate was 80 percent in Chicago – 927 murders committed, 741 solved.

READ MORE: Coworkers Rally Around River North Bouncer Who Was Shot After He Refused To Let Man Into Clutch Bar

In the early 1990s as a whole, the rate was 72 to 73 percent.

By 2005, it had slipped to 42 percent.

Last year, it was 30 percent, meaning fewer than a third of the murders committed in 2011 were solved last year.

MORE NEWS: ATM Stolen From Convenient Store In Mayfair

If there’s any good news, the 2011 figure is slightly up from 28 percent in 2010.