Boston bomings suspect Dzhokhar Tsarnaev bled for hours from neck, leg wounds, "might not have lived" if not found

Photo of suspect caught on boat in backyard
Surveillance photo of Boston bombing suspect Dzhokhar Tsarnaev on the boat that he was attempting to hide in as police cornered and arrested him.

(CBS News) More details have emerged about the Friday night capture that brought the intensive manhunt for the Boston bombing suspects to an end. Suspect Dzhokhar Tsarnaev, 19, had been hiding in a boat in Watertown, Mass. Authorities responded to a call from a local man late Friday, after he observed that a tarp covering his boat had been disturbed and there was blood in the boat.

The FBI hostage rescue teams (HRT) planned and executed their operation to clear the boat by lobbing "flash-bangs" into it, which forced the young man to climb out, according to CBS News senior correspondent John Miller. Later the agents observed that Dzhokhar had been shot in the neck and in the leg.

Based on "the amount of blood" the homeowner saw in the boat, it is likely Dzhokhar was shot as long as 20 hours before being discovered, Miller said, referring to the battle earlier Thursday that led to the death of the other bombing suspect, Dzhokhar's 26-year-old brother, Tamerlan.

It was a "fierce gun battle with police after the carjacking and the car chase, at which point they were apparently exchanging gun fire, but also throwing homemade grenades and one large satchel bomb at police officers, so he had been bleeding for a long time," Miller said.

In a photo of authorities apprehending Dzhokhar released Friday, a SWAT team medic can be seen administering an "ambu" resuscitation bag to assist him in his breathing. Another photo shows Dzhokhar climbing out of the boat under his own power, following the commands of the HRT (Hostage Rescue Team), and Miller said it is clear from the images that, "this is a guy who was very weak at this point and probably -- had he not been discovered -- he might not have lived."

A Department of Justice official told CBS News that the arresting agents used an exemption clause to the Miranda law, allowing them to first question Tsarnaev on immediate security concerns before reading him his rights.

"In a case when there are exigent circumstances -- public safety is involved," explains Miller, the exception can be invoked to quickly obtain information; namely "are there other explosives? Is there another plot to blow something up? Are there other people?"

Still, the use of the public safety exception is rare. "We almost never see that," Miller said, adding that i was last invoked to question Umar Farouk Abdulmutallab, the so-called "underwear bomber" on the Christmas Day 2009 flight into Detroit.

In the coming weeks authorities will continue to question Dzhokhar Tsarnaev, who Miller calls "an intelligence windfall." He added that the primary questions for Tsarnaev are those posed by President Obama in his addresses to Boston and to the nation throughout the week: "How did you do this? How did you plan this? And did you have help?"