More charges have been laid in what police say is the largest drug bust ever in Saskatchewan.

RCMP say a fourth suspect, 25-year-old Troy Ernest Swanson from Coldstream B.C., was arrested by Mounties in Vernon on Oct. 14.

Swanson is charged with cocaine importation and trafficking, and participating in a criminal organization. He made his first court appearance in Regina last Wednesday.

Brock Ernest Palfrey, 25, from Silverstar, B.C., 50-year-old William Bruce Larsen from Coldstream, B.C. and 28-year-old Ronald Charles Learning from Golden B.C. are facing similar charges.

The charges come after a six-month investigation, dubbed Project Faril. The massive probe involved the RCMP, the U.S. Department of Homeland Security, and the U.S. Drug Enforcement Agency.

The investigation centered on the importation of large quantities of controlled drugs that were allegedly being imported into Canada and exported into the U.S. via unmanned border crossings in rural southern Saskatchewan.

Authorities allege cocaine was destined for B.C., while mass quantities of ecstasy were destined for the U.S. Pacific Northwest. They allege the drugs would then be distributed to communities across Western North America.

In all, police seized 367 kilograms of cocaine worth an estimated $16.5 million and $1 million worth of ecstasy. A 151-kilogram seizure of cocaine near Swift Current in March 2010 is included in that tally.

Police also seized $340,000 in cash, three all-terrain vehicles, two pickup trucks and a minivan.

The investigation involved more than 100 law enforcement officers in California, Montana, B.C. and Saskatchewan.