Developments in the Boston bombing have been moving fast. Katherine Tsarnaev, wife of the late elder bomber, has stopped cooperating with the investigation. Today, the ATF is leading a search of wooded land near Dzhokhar Tsarnaev’s dorm room at Darmouth. Local and state police are also involved.

They may be searching for the bombers’ test site. The two reportedly made such quick work of building their bombs, which apparently functioned perfectly, that they moved up their attack date. Initially they had planned to strike on July 4, America’s birthday. Their quick bomb building progress enabled them to move the attack up to April 15.

While the ATF is searching for test sites, it may want to look at Hell Swamp in Hanover, MA. Residents reported explosions on the nights of March 12 and 15 — one month before the bombing. Several unexploded bombs were found at the scene after the March 15 incident. They were detonated under controlled conditions by the Massachusetts Bomb Squad. The March 12 incident included two explosions, and could have been a test of the detonation timing of the two bombs used in Boston.

The bombers reportedly used more than one design to build their bombs, which is unusual and suggests that they may have been trained and that they had time and space to build and test bombs over the course of several weeks or months.