Riverside saw its number of serious crimes drop for the second straight year in 2011, according to statistics released Monday by the Riverside Police Department.

According to the village’s Uniform Crime Report (UCR), which lists eight categories of crimes tracked by the Illinois State Police for every police agency in the state, Riverside experienced 154 reportable crimes, or a 21.4 percent drop from 2010. The UCR tracks the following categories: murder, rape, robbery, aggravated assault/battery, burglary, theft, vehicle theft and arson.

“This only reflects mandated reportable crimes which the federal government, the FBI, requires from the states,” said Police Chief Thomas Weitzel. “Everything on the list is basically a felony.”

No murders or arson cases were reported in Riverside last year. The village has not experienced an arson since 2006, and has gone without a homicide for more than a decade.

Riverside police investigated three criminal sexual assault cases (the figure does not include the one alleged rape that turned out to be fabricated, Weitzel said) after experiencing no cases of that type in 2010.

According to Weitzel, none of the incidents were random and the victim knew the alleged attacker. Two reportedly involved juvenile victims, but neither case was pursued by the Department of Child and Family Services as a rape case, said Weitzel.

Robberies were also up in 2011. Riverside police reported four robberies last year compared to none in 2010. Two of the robberies occurred within a month of one another at the 7-Eleven at 26th Street and Harlem Avenue.

After the second incident, the owner of the convenience store installed additional high-resolution video cameras for the business, after a request to do so by police.

Burglaries to residences and vehicles were up in 2011 by more than 100 percent, driven by a spree of break-ins early in the year. However, according to Weitzel, all but two of those cases have been solved. The department cleared a number of the cases with the arrests of several teenage suspects allegedly involved in a suburban burglary ring.

Two categories saw steep drops. Thefts drove crime in Riverside, accounting for 110 of the total incidents the village reported last year. But that was down 35 percent from 2010, when the village reported 169 thefts – more than the total number of reportable crimes in 2011.

Aggravated assault/battery was down to a mere one incident in 2011, versus eight in 2010. And the number is down from the high-water mark of 77 in 2003. But, Weitzel said, the dramatic change is due in part to changing reporting requirements.

In prior years, the department included misdemeanor battery and all domestic battery arrests in the report. Not so anymore. But that doesn’t mean those cases have disappeared. In 2011, Riverside reported 29 battery arrests that weren’t included in the UCR.

The lower number of reportable crimes can be a deceiving figure, said Weitzel. A drop in the UCR total does not necessarily mean criminal activity is down, just those particular categories. And while the UCR categories include some of the most serious crimes, workaday criminal activity continues at a brisk pace, Weitzel said.

“It really doesn’t affect how busy an agency is, in my opinion,” said Weitzel.

Total criminal arrests, including misdemeanor battery, DUI, petty drug crimes and various juvenile offenses were actually higher in 2011 by 3.3 percent, year over year, said Weitzel.