By Burt Hubbard and Bartholomew Sullivan
Denver Rocky Mountain News Staff Writers

High schools throughout the Denver area will remain on alert this week, with increased police and adult patrols in hallways and on school grounds.

At Chatfield High School, where Columbine High students begin split sessions Thursday, students will be required to show picture identification to enter their building beginning Monday.

Other districts have added armed police and adult monitors at high schools, restricted access and investigated various incidents.

At least three metro high schools received bomb threats last week.

Denver Public Schools swept three high schools Saturday for bombs and weapons and will sweep the other seven today and Monday, spokesman Mark Stevens said. Aurora swept its high schools Friday.

Nothing was found in either district.

Many school districts have reviewed crisis and disaster plans with local police and notified parents of increased security.

"We certainly are vigilant and alert," Englewood schools superintendent Roscoe Davidson.

The heightened security is in response to Tuesday's shooting and bombing at Columbine.

Officials denied it has anything to do with a note that surfaced Friday predicting more deaths Monday.

"The request for the photo IDs was established before those allegations came out," Jefferson County schools spokesman Rick Kaufman said Saturday. "We've increased security at all the schools."

All school buildings in the Jefferson County system will have personnel at every entrance that is not already secure.

Beginning Monday, Chatfield students will begin their split-sessions schedule. They will catch buses a half-hour early for a school day that will begin at 7 a.m. and end at 12:10 p.m. Each of the students' seven periods will be 40 minutes long.

No bus schedules have been established for the Columbine students, who will begin the afternoon sessions Thursday. Kaufman said Columbine students might not face the same photo-ID requirement, because many left wallets in backpacks that are still inside the secured building.

The state Department of Transportation is making duplicate driver's licenses available at no charge to Columbine faculty and students at its offices at 3262 S. Wadsworth Blvd. and at a licensing facility at Southwest Plaza.