Hennepin County's top prosecutor declined Friday to file charges against officers accused of supplying drugs to young men in a botched drug training program.

The announcement comes more than four months after law enforcement officials suspended the program that trains police to recognize drug use, put a state trooper on paid leave and launched a criminal inquiry into the conduct of a Hutchinson officer. The allegations first came to light in a video featuring Occupy Minneapolis activists who claimed officers offered them marijuana to smoke in front of them.

The state initially found no evidence of misconduct but suspended the program when an officer said he had seen the Hutchinson officer provide marijuana.

Following an investigation by the Minnesota Bureau of Criminal Apprehension (BCA), County Attorney Mike Freeman said prosecutors chose not to charge the officers because witnesses gave conflicting accounts of what happened and no marijuana was saved as evidence.

"At the end of the day, after that investigation had been completed, we have to evaluate whether there's sufficient admissible evidence to establish probable cause to bring a charge," Freeman said. "If it's not there, we can't charge it. That's our job."

He said witnesses were confused about dates, as well as the last names and the jurisdictions of the officers.

The officer who stepped forward also offered a different version of events than the man who allegedly received the marijuana. Freeman added that a potential "critical witness" disappeared and "did not want to be found." Freeman did, however, recommend changes to the program.

Drug Recognition Evaluator (DRE) training is commonly practiced by law enforcement across the country. It involves police examining people who already are under the influence. In the video, which did not document any officers supplying drugs, officers from jurisdictions across the state return repeatedly to Peavey Plaza in downtown Minneapolis to pick up new participants among a crowd of Occupy activists.

"I don't think you ought to send cops out who are taking a course like this -- who may not have had much experience with the urban drug culture -- to find people taking drugs," Freeman said, "without a lot of supervision, without close consultation with the cops from the jurisdiction they're in, and [without] some clear expectations [about] what they're supposed to do."

He said the program, while a good idea, "kind of failed to have the kind of direction and focus it needed."

State trooper Nick Otterson was placed on paid leave in May after a test subject accused him of being present while a law enforcement officer "handed me a bag of pot." A spokesman for the Department of Public Safety, Bruce Gordon, said Friday that Otterson was back on the job working as an "administrative assignment."

The DRE program itself remains suspended. State officials said they are reviewing its structure, processes and curriculum.

"We will not reinstate [it] until we determine the appropriate actions necessary to restore public confidence and ensure the integrity of this important program," Public Safety commissioner Mona Dohman said in a statement.

Osha Karow, an Occupy Minneapolis activist, couldn't find the logic in Freeman's decision. He said it is not surprising that witnesses had trouble recalling details since they were intoxicated when the alleged events happened. And, he added, why would the officers keep the bag of marijuana as evidence?

"I don't think they would have saved it if they had just handed it off, especially if they knew it was wrong," Karow said.

Dan Feidt, who produced the 35-minute documentary that sparked the controversy, said Freeman's decision is one example of a recent pattern of "continuous erosion of any kind of accountability for illegal operations in the government."

Star Tribune staff writer Matt McKinney contributed to this report.

Eric Roper • 612-673-1732 Twitter: @StribRoper