A third defendant accused in a federal human trafficking case involving farmworkers from Thailand pleaded guilty Tuesday to a conspiracy charge for withholding passports from workers.

Sam Wongsesanit, 40, reversed his not-guilty plea to guilty of conspiracy to commit document servitude when he appeared in U.S. District Court.

"I took their passports, but I didn’t know I was breaking the law, but now I do and I take full responsibility," Wongsesanit told U.S. Magistrate Judge Kevin S.C. Chang.

Wongsesanit was an on-site supervisor at a number of farms in Hawaii that are involved in the case. He is the third defendant — out of eight total — to plead guilty. Shane Germann and Bruce Schwartz pleaded guilty earlier this year to conspiracy.

Wongsesanit admitted to confiscating passports from the farmworkers from May 2004 to January 2008 to prevent them from fleeing. He was originally charged with two counts of conspiracy to engage in forced labor, two counts of conspiracy to commit document servitude, one count of forced labor and two counts of document servitude.

However, prosecutors dismissed the other charges in an agreement that had Wongsesanit pleading guilty to conspiracy to commit document servitude.