Saji Mohan was arrested in January 2009 on charges of possession of drugs and conspiracy to smuggle them.
A special court on Monday convicted former IPS officer Saji Mohan for illegally possessing and smuggling drugs, sentencing him to 15 years in jail.
The special Narcotics Drugs and Psychotropic Substances (NDPS) court also convicted a Haryana Police constable, Rajesh Kumar Kataria, in the 2009 case and awarded him 10-year imprisonment.
Kataria was Mohan's driver when the offence was committed.
Mohan, a former zonal director with the Narcotics Control Bureau (NCB) and joint director of the Enforcement Directorate (ED), and Kataria were arrested in Mumbai in January 2009 on charges of possession of drugs and conspiracy to smuggle them.
The duo was charged with criminal conspiracy and also under the provisions of the NDPS Act.
During the trial, the prosecution had examined 40 witnesses and also relied on four telephonic conversations between Mohan and members of a drug cartel.
Maharashtra's Anti-Terrorism Squad (ATS) had recovered from Mohan 12 kilograms of pure heroin allegedly smuggled from across the border via Jammu and Kashmir.
According to the ATS, Mohan, during his tenure as the NCB zonal director at Chandigarh, would steal more than 50 per cent of the drugs consignments seized by the bureau.
The IPS officer would then smuggle the contraband to drug peddlers in various cities, including Mumbai, the ATS said.
Kataria, as Mohan's driver, was part of the drug smuggling activity, it said.