Relatives of the students killed at Columbine High School (search) asked that the school district unseal its report on the 1999 massacre.

"We are never going to change the past, but we can change the future," said Randy Brown, who had alerted sheriff's officers to the violent rants of gunman Eric Harris (search) in 1998 after his son was threatened.

Harris and Dylan Klebold (search) killed a dozen students and a teacher before committing suicide.

Brown and others took their request to the school board late Thursday. Board president Jon DeStefano said he will get back to them.

"Locking up information that you have is not benefiting anyone at this point," said Dee Fleming, whose daughter, Kelly, was killed in the Columbine library.

The report was compiled for school district attorneys as they prepared for lawsuits. The parents say the details could help prevent another tragedy by shedding light on any warning signs that were missed or ignored.

School district attorneys have refused to release the 200-page report, saying it is covered by the attorney-client privilege exception in state open-records laws.

One attorney, Bill Kowalski, has said the report includes interviews with about two dozen Columbine staff members, copies of sheriff's documents and school records for Harris and Klebold.

Jefferson County authorities have issued more than 25,000 pages of documents on the massacre. One document indicates a school official feared Harris was "on the edge of control" and a teacher was so disturbed by a violent essay Klebold wrote that she talked to his parents and a counselor about it.

Last month, authorities released a videotape made by Harris and Klebold that shows them at target practice a few weeks before the shootings. The tape was apparently made with school equipment, and a copy of it was later discovered on a school computer.

Al Velasquez, whose son, Kyle, was killed at Columbine, urged the board to think about the benefits of learning from the tragedy.

"I'm not here for myself anymore," Velasquez said. "My son is dead. I'm here for your children, so that you don't have to come home one day without them."