As investigators from the attorney general's office persistently sought to unravel the mystery surrounding a number of Columbine documents, they caught a key break March 22.

It was the day a Jefferson County Sheriff's deputy spilled the beans about a clandestine meeting held in the aftermath of the April 20, 1999, shootings at the school.

The upshot of that previously undisclosed meeting: A draft affidavit for a warrant to search the home of Columbine High School killer Eric Harris, written in April 1998, had been deliberately kept under wraps for nearly two years.

Until the stunning disclosure by deputy Mike Guerra, no one - not the sheriff's officers or prosecutors or Jefferson County officials who were there - told anyone else about the meeting, in which it was agreed the affidavit should not be publicly disclosed.

It was "kind of one of those cover your a-- meetings, I guess," Guerra said.

The deputy had investigated Harris in 1998, but his draft affidavit was never shown to a judge and was never executed, and the case was dropped.

A statewide grand jury that took up the investigation begun by the attorney general's office found the meeting and the eventual disappearance of documents discussed there "troubling."

Although no indictments were issued, the "private meeting" and the subsequent failure to publicly disclose the existence of the affidavit "raise suspicions to the grand jury about the potential that the files were deliberately destroyed."

The twin investigations also found evidence the files related to the affidavit were erased from the sheriff's department's computer in the summer of 1999, and that a "pile" of Columbine documents was shredded in 2000.

But it was the secret meeting, at the Jefferson County Open Space Department office - away from attentive eyes -that sparked as much outrage as anything among Columbine parents.

"This is collusion," Randy Brown said. "This is criminal."

Attorney General's investigators, originally enlisted to look into the handling of a previously undisclosed 1997 report about Harris and Klebold that came to light in October 2003, discovered other Columbine documents were missing. They also began looking into the secrecy surrounding the draft affidavit.

They interviewed Guerra twice, and he said nothing about the "private" meeting. Then, on the third try, he opened up.

A summary of Guerra's third interview with investigators was released Friday after the Rocky Mountain News requested it.

Guerra said he was summoned to the sheriff's office several days after Columbine, was told to get his file on Harris then was driven to the meeting at the open space office.

He said attorneys in the room examined the draft affidavit and said it lacked enough evidence to have been approved by a judge. Someone said they had no legal exposure, Guerra said, and others told him "that they didn't see a problem with what he did."

He was told not to discuss the affidavit with anyone outside the Jefferson County Attorney's Office.

Several days later, his file disappeared, then reappeared. And a "month or two" after Columbine, he was unable to find a draft of the affidavit on his computer.

That file is missing again, and the grand jury could not determine what happened to it or to the associated computer files that also vanished.