The three convicted men were among five to face court on charges of robbery, arms trafficking and banditry for crimes carried out in 2012 and 2013.
The court found that former customs employee Gaziyav Dzhamaludinov, police officer Magomed Pirayev and local man Abdulmuslim Magomedov carried out robberies on people transporting money across the Russia-Azerbaijan border from the city of Makhachkala.
Prosecutors had alleged the criminal group also included Kizilyurt district police chief Askhabali Zairbekov. The court however acquitted Zairbekov of any role in the crimes.
The three convicted men were found to have carried out robberies that netted at least 76 million rubles (US$ 1.17 million).
The court stripped Piraev of his rank and sentenced him to 15 years in a penal colony. Dzhamaludinov and Magomedov were handed 13 and 11 years respectively.
A relative of Zairbekov present in the courtroom told Russian newspaper Kommersant that the family planned to seek compensation for two years of wages lost while he was held in remand custody.
A fifth man, policeman Mahmoud Khaibulaev, was "exempted from punishment" for medical reasons after he sustained a gunshot wound to the head in the line of duty, the court said.
