Attorney General Jeff Sessions painted a grim vision of violence in America on Tuesday, telling state law enforcement officials that a recent uptick in killings threatens to undo decades of progress and suggesting police would be more effective if they were subjected to less federal scrutiny.

In his first major policy speech as attorney general, Sessions said his Justice Department would continue to prosecute officers for wrongdoing, but suggested federal civil rights investigations could hinder their effectiveness.

"We need to help police departments get better, not diminish their effectiveness, and I'm afraid we've done some of that," Sessions told the gathering. "So we're going to try to pull back on this. I don't think it's wrong or mean or insensitive to civil rights or human rights. It's out of a concern to make the lives of people, particularly in poor communities, minority communities, live a safer, happier life."

He warned of a surging heroin epidemic, rising homicide rates in big cities and said a lack of respect for police has diminished their crime-fighting efforts.

"One of the big things out there now that's causing trouble, and where you see the greatest increase in violence and murders is somehow, someway, we undermine our respect for police and make their job more difficult," Sessions told the National Association of Attorneys General. "We're not seeing the kind of effective, community-based, street-based policing that we have found to be so effective."

In his prepared remarks Sessions also indicated that, unlike his Democratic-appointed predecessors, he believes some police officers have pulled back on enforcement because of anxiety that their actions could be recorded on video and scrutinized by the public.

Far-reaching civil rights investigations of police departments were a staple of the Obama Justice Department's attempts to overhaul troubled law enforcement agencies.

Jonathan Smith, a former civil rights attorney in the Obama administration who headed the section that investigates police departments, called the attorney general's comments "troubling" and said further alienating police and the communities they serve will not improve public safety.

"If you want to fix what's going on with Chicago in terms of the murder rate, you have to fix the police department at the same time," Smith said. "You can't do one without the other."

Sessions said he would establish a violent crime task force, underscoring an early focus on drug and violent crime that is a radical departure for a Justice Department that has viewed as more urgent the prevention of cyberattacks from foreign criminals, international bribery and the threat of homegrown violent extremism.

Yet Sessions, a former Alabama senator and federal prosecutor, made no apologies for his focus on violent crime, saying he was concerned the increase could be part of a trend.

Although it is true, according to FBI statistics, that homicide and other violent crimes have recently been on the rise, the numbers are nowhere close to where they were in the 1980s and early 1990s, and it's hardly clear that the recent spike reflects a trend rather than an anomaly.

In his prepared remarks, Sessions also pledged to "put bad men behind bars," and he stuck to that theme in his speech, telling the crowd he would prioritize cases against violent offenders, aggressively enforcing immigration laws and work to dismantle drug cartels.

Sessions said he believes drugs are driving much of the crime, and again expressed his opposition to legalized marijuana, saying "I'm not sure we're going to be a better, healthier nation if we have marijuana sold at every corner grocery store." But, while prior attorneys general have used their appearances before their state counterparts to make policy pronouncements, he offered no details about how he intends to enforce federal anti-pot laws.

Some in the audience said they're awaiting more specifics.

Colorado Attorney General Cynthia Coffman, whose office has been prosecuting marijuana drug traffickers, said she would like Sessions to witness that state's flourishing recreational pot industry before imposing a crackdown.

"I'd like to be able to share what we have learned and where we have put in place a good framework for marijuana regulations," she said. "Now for the federal government to say we're doing things wrong, or we're going to come in and take this regulation away from you without having first looked to see what we're doing is precipitous."