There’s no celebration in Denver over federal reports that crime dropped in Colorado’s largest city—because the numbers were far from complete.

The city’s police department now says clerical mistakes and software errors resulted in hundreds of crimes not being reported to the Federal Bureau of Investigation (FBI).

The mishaps resulted in the FBI not knowing about 25% of Denver’s homicides in 2012. The agency said there were 28 in 2012. But the police recorded 38.

The Denver Post concluded that the discrepancies were “vast” between what the FBI had and what local police recorded.

That would explain why the FBI reported that the city’s violent crime last year dropped 3.6%, while data compiled by the police revealed a 9.3% jump.

Similarly, aggravated assaults reportedly declined 4%, according to the FBI, while Denver police said they went up 11% from 2011 to last year.

While it’s not unusual for there to be minor differences between local police crime statistics and those held in the federal data base, observers found the Denver discrepancies to be glaring and highly unusual.

Last year, the Milwaukee Journal Sentinel uncovered similarly deceptive crime figures for Milwaukee.

The accuracy of the FBI’s data—which is held in its Uniform Crime Report (UCR)—is “important,” according to Michael Walker, a member of the FBI’s UCR subcommittee, and professor at the John Jay College of Criminal Justice in New York. “People look at UCR numbers to see if they should locate in a town, or invest in a town, or work there,” he told the Post. “If I'm a developer, first thing I'll look at is how much crime there is. I'm not going to call Denver. It's a lot easier to use the UCR.”

-Noel Brinkerhoff, Danny Biederman

To Learn More:

Officer Error, Software Trouble Skewed Denver Crime Stats, Police Say (by Sadie Gurman, Denver Post)

FBI Stats Show Violent Crime Drop in Denver, But Police Say Crime Rose (by Sadie Gurman, Denver Post)

Denver Crime Rate Report (CityRating.com)

Can FBI Crime Statistics Really be Trusted? (by Noel Brinkerhoff, AllGov)  

Milwaukee Police Lowered Crime Rate…by Misreporting Violent Assaults (by Noel Brinkerhoff, AllGov)