Authorities in Colorado have released new photos of a possible suspect in a fire and attempted bombing that forced the evacuation of a shopping mall near Columbine High School on Wednesday -- the anniversary of the massacre at the school.

The photographs distributed by the FBI Denver Joint Terrorism Task Force show the man leaving the Southwest Plaza in Littleton on a bus Tuesday night.

As with Columbine, an unexploded pipe bomb and propane tanks were discovered at the mall the following day.

The blaze coincided with the 12th anniversary of the deadly rampage that left 12 students and one teacher dead.

"We're concerned about the date, the time, things of that nature, but we don't have anything solid that would indicate any link at all other than, certainly, circumstances," Jefferson County Sheriff Ted Mink said Thursday.

Dozens of law enforcement agents were scouring security video and following other leads to identify the man seen entering the mall through a side door not normally used by the public.

The bomb didn’t explode and no one was injured in the fire. The mall reopened Thursday.

The Associated Press contributed to this report.