BOSTON (MyFoxBoston.com) - Sources say the Boston Marathon bombers initially intended to attack the city of Boston during Fourth of July celebrations.
The New York Times quotes unnamed law enforcement sources as saying Dzhokhar Tsarnaev told federal investigators he and brother, Tamerlan, intended to detonate suicide bombs at Boston's Fourth of July celebration on the Esplanade.
Sources told Fox News the brothers instead decided to build pressure cooker bombs, and when they came together faster than expected, they decided to move up their attack to Marathon Monday. A national security source told Fox News the planning for the attack showed "clear premeditation," including the decision to target the finish line. They say the brothers assembled at least four different types of improvised explosive devices and virtually all were effective. The source says in typical homegrown terror cases, only one IED is constructed.
Tsarnaev told investigators they made the pressure cooker bombs inside his brother's Cambridge apartment.
The teen also told police he and his older brother watched Internet videos by Al Qaeda operative Anwar al-Awlaki. Al-Awlaki was an American-born cleric who was killed in 2011 by a drone strike in Yemen.
The new details were reportedly a part of statements made by Tsarnaev on April 21, prior to being read his Miranda Rights. Investigators invoked an exception to the Miranda Rule in the interest of public safety.
More clues are certain to come Dzhokhar Tsarnaev's laptop computer.
Two anonymous investigators also told The New York Times Thursday that DNA and fingerprints found on bomb components from the scene of the bombings do not match those of Tamerlan Tsarnaev's widow, Katherine Russell.
On Wednesday, three of Dzhokhar Tsarnaev's friends from UMass Dartmouth were arrested for lying to the feds and attempting to destroy evidence that was later found in a landfill. One of them, Dias Kadyrbayev, according to a criminal complaint, grabbed Dzhokhar Tsarnaev's laptop from his dorm room.
Kadyrbayev said he took the laptop because he didn't want Dzhokhar Tsarnaev to get into trouble.
According to The Boston Globe, four days after the deadly explosion, he turned the laptop over to the feds. Right now, they are analyzing the contents of the hard drive.
Tamerlan Tsarnaev was killed on April 18 following a shoot out with police in an East Watertown neighborhood. Investigators say his younger brother drove over him while trying to flee the scene. Dzhokhar Tsarnaev was captured on April 19 after he was found hiding in a boat in a Franklin Street back yard.