BONNERS FERRY, Idaho (AP) - Bomb threats scrawled on walls have become such a problem at a northern Idaho school district that a restroom monitor has been assigned to have high school students sign in and out of bathrooms. The Spokesman-Review reports (http://bit.ly/YMaG5k) that there have been nine bomb threats at the Boundary County School District since late October. Officials say four have been written inside restrooms at Bonners Ferry High School. Three other bomb threats were found at the middle school and two others were called into the county's 911 dispatch center. Investigators say they have identified several juvenile suspects but believe more students are responsible. An $11,000 award is being offered to find out who is making the bomb threats that have led to evacuations and calling in bomb-sniffing dogs.