RED LAKE, Minn. (AP) – The teenage son of the tribal chairman has been arrested in connection with last week’s shootings on a Minnesota Indian reservation, a law enforcement source with knowledge of the investigation said Monday.

Louis Jourdain, son of Floyd Jourdain Jr. and a student at Red Lake High School, where most of the killings took place, was arrested Sunday, the source told The Associated Press.

The younger Jourdain was arrested as part of an investigation into a potentially wider plot, the source said.

A biography of Floyd Jourdain posted on his Web site in February 2004 gave Louis’ age as 15, meaning he would now be 16 or 17.

Nine people were killed in last Monday’s attacks before 16-year-old gunman Jeff Weise, also a student at the school, took his own life.

Investigators said last week that Weise acted alone.

in the rampage on the Red Lake Band of Chippewa’s reservation.

Weise, who had a history of depression, first shot to death his grandfather and his grandfather’s girlfriend, then went to school and killed a security guard, a teacher and five students.