Hillsborough, N.C. — A teen charged with holding a student and a teacher hostage at a Chapel Hill school last spring will be tracked by satellite as part of an agreement to be released on bond.

William Barrett Foster agreed Friday to wear an electronic bracelet linked to a Global Positioning System satellite and to remain in the Raleigh apartment complex where his parents live if he could be released from Dorothea Dix Hospital on a $40,000 bond.

"This is just another level of safety," said Capt. Charles Blackwood of the Orange County Sheriff's Office. "The unique thing about the system is we monitor you wherever you are."

Foster has been undergoing psychiatric treatment at Dix for several months. He is due back in court next month.

Last month, he pleaded not guilty and not guilty by reason of insanity to charges stemming from the April 24 incident at East Chapel Hill High School.

A teen entered a classroom after school and threatened to kill civics teacher Lisa Kukla and a student, Chelsea Slegal. The teen was armed with a shotgun, an air pistol and a hunting knife, police said.

Kukla was eventually able to talk the teen into firing the weapon out the window. The teen ran from the school and was later arrested.

Both Kukla and Slegal agreed to the terms of Foster's bond.

The GPS monitoring system is a pilot program in Orange County. When it is launched next month, it usually will keep an eye on domestic violence offenders, but District Attorney Jim Woodall said he felt Foster's case was unique.

"It's our goal to pick people we're sure will comply," Blackwood said.

Foster's parents are paying $200 a month for the device, and Woodall said that he believes the teen will abide by the rules with his parents' support. If Foster does leave the apartment complex or tries to get rid of the ankle bracelet, authorities will be notified immediately.

"There will be an immediate response and he will be put in custody and brought before a judge," Woodall said. "When I say immediately, I mean within minutes."