Denver police response times have increased sharply over the past year, jumping by an average of more than a minute in even the most urgent incidents, police department data show.

The slowing response came despite a more than 11 percent drop in the number of citizen calls for police service, from 280,150 between January and October of 2012 to 248,594 during the same period this year.

Average response to “lower priority” calls — such as car theft reports, burglar alarms and assaults that are no longer unfolding — climbed the most compared to last year. But callers reporting more pressing emergencies such as domestic violence, missing children, weapons offenses and child abuse waited more than a minute longer on average than they did a year ago.

Police officials have grappled with slowing response times as the department’s ranks shrink due to retirements, departures and budget cuts that kept the city from hiring officers for five years. The data, obtained by The Denver Post through an open-records request, quantify the problem.

Calls for police service in Denver are prioritized on seven levels. The highest priority calls, described as “critical incidents,” are ranked Priority 0 while calls of the lowest priority, such as theft and fraud reports, are ranked Priority 6.

Response to those lowest priority incidents slowed by 6.7 minutes this year, from an average of more than 34 minutes to an average of more than 41. Officers last year took 21.1 minutes to respond to calls ranked Priority 3, or “public need,” incidents such as assaults that are no longer in progress, drug complaints and shoplifting, compared to 24.6 minutes this year.

And it takes officers an average of 7.2 minutes to respond to “critical incidents,” compared to the 5.9 minutes it took to respond to the same kinds of incidents last year.

“Absolutely, 100 percent, it’s the result of not having enough officers on the street,” said Lt. Matt Murray, the department’s chief of staff.

The addition of 29 officers last month and 35 more police academy graduates in upcoming weeks brings the department’s force to 1,398, but the newest officers won’t start patrolling the streets on their own until early February. That’s an improvement, officials say, but not when compared to the 1,550 officers the department had in 2008.

Murray said the department’s data analysts found a correlation of more than 80 percent between staffing levels and response times.

“As soon as these guys hit the streets in February, you’ll immediately see better response times,” he said.

Officials studying the slowing response, which next year will include the city auditor’s office, have said the delays are partly the result of it taking longer for dispatchers to find an available officer.

“The basic problem is that there are a higher number of calls than there are officers who can handle them. It’s a simple supply and demand equation,” said Lt. Vincent Gavito, vice president of the police union. “If you’re truly a victim, why should you have to sit around and wait one or two hours for an officer to come? It’s like you’re victimized twice.”

The union has said Chief Robert White’s sweeping staffing changes have added to the delays — an assertion that Murray rejected.

Gavito said he is hopeful that tweaks to White’s staffing plan will improve response times next year.

The auditor’s office announced last month it would investigate the reason for the delays after fielding a slew of complaints from citizens and officers alike. And this summer, the department revamped the way it responds to rape victims who walk into hospitals after victims sometimes waited two to three hours for an officer to respond.

One woman left St. Anthony’s Hospital in Westminster in August rather than continue waiting after it took a Denver officer more than two hours to arrive, according to dispatch records obtained by The Denver Post.

“If you have to wait several hours for a police officer on an accident report, it’s not good customer service,” Murray said. “The problem is, there is no add-water fix here. It’s about bodies on the street.”

White wants officers to respond to the highest priority calls in as close to six minutes as possible, Murray said, adding the officials are going to study current times against those in years when the agency was fully staffed to try to determine what times are optimal.

But officials shouldn’t set a hard and fast standard for officers’ response to certain calls, said Thomas Aveni, executive director of the New Hampshire-based Police Policy Studies Council. Doing so can create unrealistic expectations and expose the city to lawsuits, he said.

Historically, departments have strived to respond to the most urgent of calls within three to five minutes, Aveni said. But that has proved problematic.

“That’s been pretty much the constant ideal,” he said. “It’s really hard to deliver, unless you have got no traffic, you’ve got plenty of cars free and they happen to be relatively close to the incident.”

Sadie Gurman: 303-954-1661, sgurman@denverpost.com or twitter.com/sgurman