A former Seattle police officer pleaded guilty to smuggling hundreds of pounds of marijuana to Baltimore.
Police said Alex Chapackdee worked with his brother-in-law and two others to transport the drugs.
Investigators said they began looking into after a confidential source reported that his brother-in-law had been paying him $10,000 a month to keep an eye on marijuana grow houses and to provide him with information about law-enforcement activities.
According to police, the 44-year-old made cross-country trips in his recreational vehicle in September, October and November of last year.
The U.S. Attorney's Office said after his plea Monday prosecutors would recommend the minimum sentence of five years when Chapackdee's sentenced next March, though he could face up to a maximum of 40 years.
The Associated Press contributed to this report.