Lt. Bob Kroll (center), heads the Minneapolis police union. Renee Jones Schneider/Star Tribune

Two of Minneapolis' top law enforcement officials have waded into the highly charged debate over the existence of the so-called “Ferguson effect.”

Police union chief Lt. Bob Kroll said in a radio interview that heightened scrutiny following unrest after the fatal police shooting of an unarmed black man in Missouri last year has made some cops more hesitant to use force, even when the situation calls for it.

Speaking with with Boston’s WBUR last week, Kroll said that criticism of police behavior following the death of Michael Brown is largely responsible for the rise in violent crime in Minneapolis.

“In my 27 years, morale is at an all-time low and officers don’t go into this job to work that way,” Kroll said in the interview, which aired last week, “they go in to be aggressive, work hard, proactive patrol, and be clear: they’re not afraid of the criminals, they’re afraid of fallout and maintaining their job.”

He continued: “There’s no measuring what officers do or don’t do when they’re supposed to be working proactively. Of course they’re going to take their calls, but the proactive police activity has really dropped off.”

Kroll previously told KSTP-TV that he assumes that some cops are "second-guessing themselves, thinking, 'Should I engage? Should I do this, or should I not?'"

Kroll said he agreed with the recent comments of FBI director James Comey, who suggested that police anxiety in “the era of viral videos” was one possible explanation for the jump in violent crime in several large U.S. cities. Although he conceded there was little evidence to support the claim, Comey's remarks at a policing conference in Chicago last month reignited public debate on the issue.

Not everyone in the room that day shared Comey's view, including MPD Chief Janeé Harteau, who said this week that the officers in her department were as “engaged” as ever.

“I think if you were to talk to the chiefs that were there, I think they would say that” they were philosophically at odds with the idea, Harteau told the Star Tribune this week.

“In Minneapolis, everything is up, as far as our productivity and engagement, so I don’t see that,” said Harteau, who has pledged a "holistic" plan  to tackle rising crime. “So there are times when you can look at things nationally, and you should, but you also have to look at your own city.”

The White House also distanced itself from the controversial remarks, which drew sharp criticism from activists who argued that there is no data to support it.

Kroll said that many officers continue to take heat for simply their jobs.

Asked by a radio caller about the firing of a South Carolina officer after a video surfaced of him yanking a female high school student from her desk, Kroll said that officers are “sick of being Monday morning quarterbacked and everybody seems to know our job better than we do, lacking all the training and experience."

He later added: “I don’t think any officers like to use force. But what people need to remember is you’ve got a duty to comply with what the officers tell you."

The full interview can be found here.