Investigators believe the explosives used Monday were pressure cookers placed in nylon bags. The blasts killed three people and injured at least 176 others.from FBI reviewing before-and-after photos of bag at Boston Marathon blast scene
Among the photos under review are the two above, which were given to NBC station WHDH of Boston by a witness.
The first picture shows a bag next to a mailbox along a barricade on the marathon route. The second — which the station said it had blurred because of its graphic nature — appears to show no sign of the bag.
The person who took the pictures told WHDH that as long as an hour may have passed between the times the two photos were taken.
In other words, the bomb was sitting for about an hour where any cop with anti-terrorism training should have noticed it. So who was assigned to that area? Was this part of the "drill?"