There is new evidence on the Boston Bombing case that the two suspects were trained to carry out an attack. The bomb was very sophisticated, which leads to this thought. Homemade bombs made from pressure cookers are quite common in the Middle East; once there was even an article published on how to make one!
Tamerlan, one of the suspects was killed several days after the attack in a shootout with police. Dzhokhar, the younger brother, was captured in the manhunt and is now at a medical detention center. They dropped and detonated two bombs near the finish line of the Boston race, killing three people and injuring more than 260 others.
More investigation will proceed.