IRON MOUNTAIN, Mich. -- A Wisconsin judge has set a $3 million cash bail for a Michigan man charged with shooting and killing three teens at a river on the state border.

Marinette County District Attorney Brent DeBord had asked for $5 million bail, calling Scott J. Johnson, 38, of Kingsford, Mich., an "extreme flight risk" because he spent time in the military and has traveled extensively.

Johnson appeared by videoconference and answered a handful of questions from Marinette County Circuit Judge Tim Duket with just "yes" or "no."

Johnson has been charged with three counts of first-degree intentional homicide. DeBord said two more charges of attempted first-degree intentional homicide and sexual assault could be added.

A criminal complaint said Johnson assaulted a woman at the river the day before the shootings. A criminal compliant said Johnson had been planning the shooting for years.

A Michigan prosecutor said he hopes Johnson will be federally charged for one of the deaths. Dickinson County Prosecuting Attorney Chris Ninomiya said in a statement Thursday that he has spoken with federal authorities about charging Johnson for the death of a man found in Michigan.

Ninomiya said federal prosecutors could seek the death penalty, which is not possible in Wisconsin or Michigan.

A spokeswoman for the Western Michigan U.S. Attorney's office said it's looking into whether it has jurisdiction.