The fire at the JFK Presidential Library and Museum in Boston was caused by careless disposal of smoking materials. The fire was reported just minutes after the second Marathon terror explosion blocks away in Copley Square. Boston officials had initially feared that the fire at the library might have been connected to the bombings.

While the investigation of the fire went along in a typical manner, there is no doubt that security video, especially cameras of retail establishments on Boylston Street, played a major role in identifying two people of interest. Video analytics, an increasingly popular tool with retail chains, may have also helped speed up review of the many images from cameras and smartphones equipped with cameras.

A final decision to release photos of the two people of interest came after a law enforcement official experienced in reviewing video noticed Suspect 2 slipping his backpack off and placing it on the ground, then working his cellular phone and then walking away. Just after that, the second explosion happened.

In light of what had just happened, and the library is of course a high profile place in Boston, the fire caused a lot of speculation, Boston Fire Department spokesman Steve MacDonald said in a statement to the media.

The fire started in an HVAC system in a part of the library and museum complex that opened in 2011 and houses offices, a classroom and some archival material. At the time, the building was evacuated.