Crime in Colorado increased in 2015 over 2014 in nearly every category reported by the Colorado Bureau of Investigation. After controlling for increases in the state’s population, overall crime reported increased by 4.4% last year.

The highest increases in population-adjusted crimes were auto thefts, 25.5 percent increase; homicide, 14.3 percent increase; and rape, which increased by 8.9 percent.

Last year, 172 homicides were reported statewide, 53 of which occurred in Denver. However, Denver only made 30 arrests for murder or non-negligent manslaughter.

Sonny Jackson, a Denver Police spokesman says there are a myriad of reasons causing more crimes to be reported than arrests made – mainly because cases are still open.

“You can see that in any jurisdiction and any crime,” Jackson said. “We would love to be able to solve them all – sometimes we can know who did it but do not have enough evidence to take it to court.”

In Denver, only 23 percent of all reported rapes resulted in arrest; that’s 131 arrests made from the 551 rapes reported last year.

Rape has been a historically challenging crime to solve, and one criminologist pointed out that the increase in reporting could actually be considered a success.

“Maybe a victim advocacy message got out better,” said Jennifer Bradford, an assistant professor of criminal justice at Metropolitan State University. “This could have been a year when it was better reported.”

Bradford also suggested that overall, one year of crime data is not enough to make a trend. Really, statisticians and criminologists focus on longer trends – like 10 years long.

“A good analogy is to think of the stock market,” Bradford said. “If we were to look at 2009, we would see a dip in all stocks, bonds and mutual funds, but if we look at the 10 year total, you see a steady increase over time, and that’s really how you should look at crime.

“If you look at just one year, that may be an anomaly.”

Bradford also pointed out that there could be many factors influencing the raise in violent and property crimes throughout the state.

“Who knows what directly is contributing to the numbers,” Bradford said. “There are many things that could be causing it, the legalization of marijuana, or maybe an increase in gangs, an increasing in mass shootings; any of those things could be contributing – I would caution against saying that’s a direct cause until that is better reported statistically.”