Investigators on Thursday released a third photo of the person. In two photos, he is seen entering a stairwell and carrying a white plastic bag. The latest shows him on an escalator inside the Southwest Plaza Mall.
Firefighters found the devices after the fire that prompted the evacuation of the mall around noon Wednesday. No one was injured and the devices didn't explode.
Authorities are investigating the source of the fire, including whether it was caused by the failed detonation of a bomb, said West Metro Fire Rescue spokeswoman Cindy Matthews.
Wednesday was the 12th anniversary of the shooting rampage at nearby Columbine High School and officials expressed concern that it could be somehow linked.
"The fact that has happened on April 20, 12 years later, near the school and with similar devices is very disturbing," said Jefferson County sheriff's spokeswoman Jacki Kelley.
A possible connection to Columbine will be explored.
"It's something that can't be ignored and won't be ignored," Kelley said.
The mall is about two miles from the school, where two student gunmen killed 13 people and themselves on April 20, 1999, in a rampage that stunned the nation.
Unexploded pipe bombs and a propane tank with explosives attached were found in the school cafeteria after the shootings, and it was unknown whether the bomb and propane tanks' placement in a hallway in the mall's food court area were inspired by Columbine. Sheriff's spokesman Mark Techmeyer said a quick thinking security guard extinguished the flames with a fire extinguisher. The guard's name was not immediately released.
Through the years, students across the country have been accused of threats and incidents modeled after Columbine.
"It certainly appears to have a link to Columbine, in that it's a similar style crime and that the intent was obviously to hurt and kill innocent people," said Brian Rohrbough, whose son Daniel was among those killed at Columbine. "The kind of crime like Columbine will motivate a certain segment of the population to attempt the same type of crime, whether they're doing it because they're purely evil or in addition to being evil, they just want attention, I don't know."
FBI spokesman Dave Joly said the person of interest seen on surveillance video entered a stairwell that isn't typically used by the public.
He is described as a white male with graying hair and a silver mustache. Photos taken from surveillance show him in a dark cap, gray and white striped shirt, dark jacket, blue jeans and dark shoes. He is seen entering a stairwell and carrying a white plastic bag.
Joly said it was too early to speculate whether it was an act of terrorism.
Sheriff's officials said there are usually about 6,000 to 10,000 people in the mall around noon each day. Shoppers and about 300 mall employees left after the fire.
Matthews, the fire rescue spokeswoman, won't say whether gas from the propane tanks burned in the hallway that damaged some drywall and equipment on the wall, saying the matter remained under investigation.
A daylong search didn't turn up any other explosive devices in the mall, which would be open for business Thursday.
About 25 schools were on lockout as a precaution, meaning access is restricted to one point, according to the Post. Classes had been canceled at Columbine High School in remembrance of those killed in the shootings.
Eric Harris and Dylan Klebold wounded several students and killed 12 and one teacher before shooting themselves.