'It took five years, a state grand jury and key evidence from a reluctant witness, but families who lost children in the attack on Columbine High School finally had their worst suspicions confirmed: Top Jefferson County leaders knew something awful about prior police investigations of killers Eric Harris and Dylan Klebold, and they’d known it since shortly after the 1999 shootings.

 The officials knew plenty, denied most of it, and hid as much as they could for as long as they could. Called by Colorado Attorney General Ken Salazar, the grand jury released a summary of its findings two weeks ago. Although the probe of missing police documents resulted in no indictments, it did raise questions about “suspicious” actions by the Jefferson County Sheriff’s Office brass, including the shredding of a large pile of Columbine files.

Most stunning of all, the report charged that a few days after the massacre, several high-ranking county officials met secretly and resolved to suppress key documents stemming from the JCSO’s earlier investigation of Harris, to treat them as if they didn’t exist — in short, to lie about them.'

Read more: Columbine: Anatomy of a Coverup