Washington: The surviving Boston Marathon bomber Dzhokhar Tsarnaev, 19, arrived on Boylston Street near the finish line about five minutes before the deadly April 15 explosion that killed three people and injured over 180, according to the US case against him.
He was wearing a white baseball cap and a black jacket like the one FBI found when they searched Tsarnaev`s dorm room at University of Massachusetts, Dartmouth, according to an affidavit filed in US District Court by FBI Special Agent Daniel R. Genck.
A video taken at 2:45 p.m, from a surveillance camera at The Forum restaurant, near the marathon`s finish line on Boylston Street and the site of the second explosion, shows a man believed to be Tsarnaev slipping his backpack off his back and onto the ground, Genck wrote.
The man stays near his bag for the next four minutes, looking at his phone and apparently taking a picture, according to the complaint. A photograph taken from across the street shows the bag laying at the man`s feet.
"Thirty seconds before the first explosion, the suspect brings his phone to his ear and keeps it there for 18 seconds. As the first bomb goes off, the crowd reacts and begins streaming away from the marathon`s finish line.
"Bomber Two, virtually alone among the individuals in front of the restaurant, appears calm," Genck writes describing Tsarnaev as "Bomber Two" instead of "Suspect Two".
The suspect walks away from the finish line, leaving his bag behind. Ten seconds later, the second explosion occurs.
"I can discern nothing in that location in the period before the explosion might have caused that explosion, other than Bomber Two`s knapsack," Genck writes.
The affidavit also provided a detailed account of the events Thursday night and early Friday leading to the death of Dzhokhar Tsarnaev`s older brother Tamerlan, 26, in an encounter with the police.
According to the affidavit, about seven hours after the FBI released photos and videos of the brothers, then known only as Suspect 1 and Suspect 2, a person carjacked an SUV at gunpoint in Cambridge shortly before midnight.
Either Dzhokhar or his now-dead brother, Tamelan - it`s not clear which brother was the armed man - points and gun at the victim. "Did you hear about the Boston explosion?" the suspect asks. "I did that." The man removes a bullet from the gun`s magazine, puts it back in and declares: "I am serious."
The victim and the suspect drive and pick up a second man. The suspect and the second man talk in a foreign language.
The gun-wielding suspect demands money from the victim, who gives him $45. The two carjackers demand the man drive to an ATM, where they take money from the victim`s account. The victim escapes when the two carjackers stop at a convenience store.
The FBI reviewed footage from the convenience store`s surveillance camera and agents identified the two suspects at Dzhokhar and Tamerlan Tsarnaev.
Police encounter the stolen vehicle in suburban Watertown. Police and the carjackers exchange gunfire, and the carjackers throw several explosives at police.
The FBI later recovers two unexploded improvised explosive devices from the street, along with the remains of multiple exploded IEDs. One of the suspects is injured and remains at the scene while the other flees in the stolen car.
The IEDs recovered at the scene in Watertown and the IEDs set off at the Marathon have the same design, used the same brand of pressure cooker and both contained BBs (ball bearings) "contained in an adhesive material." Both also used a green-coloured hobby fuse, the affidavit says.
Police searched Dzhokhar Tsarnaev`s dorm room at the University of Massachusetts-Dartmouth on Sunday. They find a "large pyrotechnic," BBs and a white hat and black jacket matching those worn by the second bomber, the affidavit said.