The 1st blast occurred at 4:09:43 race clock, (about 2:50 PM)
Location of 2nd Bomb Blast
Photo of Dzhokhar Tsarnaev (white hat) Near (8yr old) Martin Richard (blue circle) Who Died in Boston Bombing (lower red circled image allegedly Tsarnaev’s backpack bomb). The FBI affidavit appears to refer to this photo.
Bomber suspect Dzhokhar Tsarnaev at left in white cap worn backwards.