DENVER (AP) — A man has acknowledged planting a homemade bomb at a Colorado shopping mall on the 12th anniversary of the Columbine High School shootings.

Earl Albert Moore, 56, pleaded guilty in Denver federal court Friday to one count of using a destructive device in a crime of violence.

An April 20 fire at the Southwest Plaza Mall in Littleton and the discovery of the bomb raised fears it was timed to coincide with the anniversary of the 1999 school shootings at nearby Columbine in which two students killed 13 people and then themselves.

Moore later told investigators the bomb had nothing to do with Columbine and that he did not realize it was the anniversary of the shootings, according to a plea agreement released Friday.

In exchange for the guilty plea, prosecutors dropped a second charge of arson. The U.S. attorney's office said Moore faces a mandatory prison term of at least 30 years when he is sentenced in March.

Asked in court why he planted the device, Moore said he was upset about "a domestic thing."

The Denver Post (http://bit.ly/uwzNlj ) reported that Moore said, "I didn't have any intention of hurting anybody."

Moore said he drained the propane tanks connected to the device before leaving it.

Moore used to live in Colorado and has bounced around the federal prison system for the last 27 years. He was released from prison in Estill, S.C., a week before placing the bomb in the mall.

The bomb components, matches and debris were sent to an FBI laboratory in Virginia. DNA found on the material matched Moore's DNA profile in a national database and investigators started a nationwide search for him. He was arrested six days later at a grocery store in Boulder after being spotted drinking coffee at the store's Starbucks.

Court records show that Moore — who lived in Colorado at least part-time from the mid-1980s to 2004, including five years at a federal prison at Englewood — has a history of offenses dating back to 1966, when he was 20, including allegations involving firearms and explosives.

In his latest prison stint, Moore served time after pleading guilty in May 2005 to robbing a Crab Orchard, W.Va., bank of $2,546. He was also sentenced to five years of supervised release in that case.

Moore was supposed to report to West Virginia within 72 hours of his release but didn't.