A 42-year-old man has been sentenced to 20 years in prison after he was convicted of trafficking drugs to Hawaii.

U.S. District Judge Kimberly Mueller sentenced Epati Malauulu of Suisun City, Calif. Wednesday for conspiracy to distribute methamphetamine.

Malauulu distributed high-quality crystal methamphetamine to Hawaii from Northern California. Officials said he mailed over 15 pounds of methamphetamine to Oahu between August 2014 and June 2015, according to a news release.

Three other men — John Ortiz, 45, of Vallejo; Algernon Tamasoa, 28, of Sacramento; and Francisco Poloai, 45, of Dixon were charged with conspiracy.

Both Ortiz and Tamasoa pleaded guilty to methamphetamine trafficking activity. Poloai’s trial is scheduled for September.

Officials said the drug ring investigation ultimately resulted in charges against 44 people in Hawaii and four people in Northern California.