This story was updated at 2:15 p.m. ET Thursday
The acting administrator of the Drug Enforcement Administration said the police may be "reluctant to engage" for fear "rightly, or wrongly, that you become the next viral video," adding a new voice to the debate over public scrutiny of law enforcement.
Chuck Rosenberg told reporters at a pen and pad session in Washington on Wednesday that "I think there's something to" the concept known as the Ferguson effect, which maintains that police have stopped engaging with the public in the same way as scrutiny of their interactions with minorities increased over the past year.
Rosenberg said the issue deserved more study and better data. And he offered praise for FBI Director James Comey, who first raised the idea in a pair of speeches in Chicago in recent weeks. The White House has pushed back on that idea.
"I think Comey was spot on," Rosenberg said. "It's hard to try to measure. It's a hard thing to grasp ... We're not entirely sure what's going on and we ought to try and figure it out."
Rosenberg spoke as the DEA unveiled a new 2015 Drug Threat Assessment. Cocaine use has declined, but abuse of methamphetamine, heroin and opioid substances still pose a big problem across the country, the assessment said. Overdose deaths are now the nation's leading cause of death by injury, tallying more than 46,000 annual fatalities and surpassing car accidents and firearms incidents, the DEA said.
The DEA leader said he attributed a spike in violence in some big cities this year to "roiling and violent" heroin markets, the widespread availability of firearms and finally, more "trepidation" among police officers.
As a longtime federal prosecutor, Rosenberg said he understood and even approved of efforts by the Obama administration and Congress to reduce the disparity in punishment among criminals who traffic in powder cocaine and those who deal with it in rock form. Those punishments have had a disproportionate impact on African-Americans and Hispanics in the justice system. But Rosenberg said he'd prefer to step back and see how those changes are working before further relaxing mandatory minimum sentences first imposed during the War on Drugs.
Rosenberg said the recent early release of about 4,300 convicted drug offenders was "not going to keep me up at night" but that he's worried about whether there are enough resources to support those people when they leave institutions.
"Do cities around America really have the resources to take more mentally ill folks, more jobless folks? I don't know. That's what worries me," he said.
Turning to the fight against drug abuse, Rosenberg said he'd pursue a mixture of traditional enforcement, demand reduction and community outreach, and more diversion efforts and partnerships with doctors and pharmacies.
Rosenberg said he's not opposed to changes to long prison sentences for nonviolent offenders. He added that the U.S. can't prosecute its way out of problems like addiction and mental illness. And, Rosenberg said, prosecutors will still have plenty of leverage to secure guilty pleas and cooperation even if Congress dials back some penalties.
"On the broader issue of sentencing reform, I fully support the Department of Justice's efforts to make drug sentencing more proportionate to the offense. I support this precisely because ... we aren't going to jail our way out of the problems we currently face," he said.