The leader of a Michigan militia group charged this week with conspiring to kill law-enforcement officers was described Tuesday as a private, family-oriented man who nurtured a festering mistrust of governmental authority, according to people close to the family.

"On the inside of this man's brain, something evil lurks, and until you get to know him, you don't know it," said Andrea Harsh, who was engaged to David Brian Stone Sr. until the couple broke up last year.

In an indictment Monday, federal authorities named Mr. Stone as leader of the Hutaree and accused him and eight members with plotting to spark an uprising against the U.S. government by killing police. Along with Mr. Stone, seven other men and one woman from Michigan, Ohio and Indiana are in being held without bond on weapons and sedition charges.

The indictment said Hutaree had practiced attacks and other military maneuvers for more than a year, and had planned to kill a law-enforcement officer, then use homemade bombs to attack officers who attended the funeral.