The chairman of the Red Lake band of Chippewa (search) confirmed Tuesday that his son was arrested in connection with last week's deadly school shootings but maintained that the teen is innocent.

"My heart is heavy as a result of the tragic events that unfolded here at our nation," Floyd Jourdain Jr. (search) said in a statement. "But it is with optimism that I state my son Louis's innocence. He is a good boy with a good heart, who never harmed anyone in his entire life."

"I know my son and he is incapable of committing such an act," Jourdain said.

The younger Jourdain, 16, was arrested by federal authorities on Sunday.

Jeff Weise (search), 16, killed nine people in an attack on the reservation on March 21 before taking his own life. Five of the dead were students, killed at the high school. It was the worst U.S. school shooting since the attacks by a pair of students at Columbine High in Colorado.

Federal authorities had announced an unidentified juvenile's arrest on Monday, and a law enforcement source speaking on condition of anonymity had identified the boy to The Associated Press as Louis Jourdain (search). The source said the arrest was part of an investigation into a potentially wider plot.

A government official briefed on the investigation told AP that prosecutors were contemplating charging Jourdain as an adult with conspiracy to commit murder. The official spoke only on condition of anonymity because the investigation is continuing.

Authorities began to suspect that Weise may not have plotted the attack by himself after examining his computer and e-mails he exchanged with Jourdain, this official said.

The law enforcement official said FBI behavioral analysts brought into the case also doubted that Wiese acted alone, based on personality traits they identified.

More arrests are possible, said this official and the law enforcement official.

In announcing the arrest Monday, U.S. Attorney Tom Heffelfinger had declined to provide any details on Louis Jourdain's role in the case.

The Washington Post, citing two unidentified law enforcement officials familiar with the investigation, reported Tuesday that Louis Jourdain was suspected of helping Weise plan the assault and had expected to take part.

Red Lake High School principal Chris Dunshee said Louis Jourdain was not a discipline problem and didn't seem to be part of Weise's circle of friends.

"He's one of those kids that I didn't have a lot of contact with, because he really wasn't a discipline problem. He was a pretty good student, to tell you the truth," Dunshee said.

The principal said he felt sorry for Floyd Jourdain: "My heart goes out to him, he's such a good guy. If it could happen to his son, it could happen to anybody, because Buck is a good parent."

Dunshee said the district's two elementary schools would reopen Monday but the high school complex, which includes the middle school, might be closed for the rest of the school year.

Floyd Jourdain was 40 when he was sworn in last summer as Red Lake's youngest-ever chairman. On his Web site, he writes about post-college work counseling people in alcohol recovery and celebrating his own 20 years of sobriety in June last year. Among the issues he pledged to address is the concerns of young people.

At a news conference in the days after the shooting, he spoke of tribal members keeping track of their kids: "This is a wake-up call to us all. We need to spend more time with one another and paying more attention to our young people and what they're doing and what they are saying."

On Jourdain's personal Web site, a collection of family photos includes one of him and Louis with the caption: "My pride and joy Louie who always shares his school achievements with me."