Federal prosecutors and the Federal Bureau of Investigation spent 22 months finishing last month looking into allegations that an undisclosed number of officers stole property.
The investigation also included a grand jury probe, which ended without any indictments.
Wendy Olson, the U.S. attorney for Idaho, concluded there would be no charges, according to a Dec. 18 letter she sent to Boise Police Chief Mike Masterson.
Olson told Masterson that there is insufficient evidence to prove beyond a reasonable doubt that the subject officers willfully violated the Fourth Amendment rights of any specific individual.
The investigation was thorough and lengthy, according to Olson. The FBI also took additional investigative steps at her offices request, Olson wrote in the letter, obtained by the Idaho Statesman through a public records request to the city of Boise.
Boise Deputy Chief William Bones said the city was not consulted or briefed.
Privacy protections afforded law enforcement and grand jury investigations limit the information that may be shared, which as reflected in (Olsons) letter, did not provide the department with information on the allegations, Bones wrote in response to questions from the Statesman.
Early last year, the Boise Police Department, the FBI and the U.S. Attorneys Office would not admit an investigation was underway.
Several sources familiar with the matter told the Statesman that former Boise Officer Rob Berrier one of only 14 ever awarded the departments Medal of Honor for extraordinary acts of valor and heroism was under investigation. But BPD refused to confirm that or give a reason why.
Police officials said only that Berrier, who started working for the department in December 1995, resigned in 2011. He lost his job for having an inappropriate sexual relationship with a confidential informant and later had his police certification stripped by the Idaho Peace Officers Standards and Training Council, according to his POST decertification file.
Berrier could not be reached for comment.
After Olson sent her letter, Bones wrote to the Statesman that the department was not at liberty to confirm investigations into possible officer misconduct, in order to maintain the integrity of any investigation.
Early last March, when the federal investigation was first revealed, there was no indication that other officers were implicated.
The U.S. Attorneys Office in recent weeks declined to provide any details on the investigation. As a result, its unknown how many officers had been under scrutiny.
Its also unclear how many of the officers who were investigated have resigned or were fired. Olsons letter indicates only that some of the officers who were the subject of this investigation are no longer with the Boise Police Department.
Masterson was notified at the outset of the federal investigation that the probe would focus on the actions of one former officer, Bones wrote. Bones did not identify Berrier as that officer, but the dates of employment for that officer match Berriers.
No details were provided that could help identify any of the other officers who were investigated.
The department, Bones said, has made changes after the investigation to ensure internal and public confidence in its searches.
The Boise Police Department has strengthened its policies involving evidence collection, control and storage, Bones wrote. New supervisors have rotated into assignments to implement and oversee those policies, with police command oversight.
John Sowell: 377-6423, Twitter: @IDS_Sowell