The lone surviving suspect in the Boston Marathon bombing is still lying wounded in hospital and for now is unable to talk to investigators.
Massachusetts Gov. Deval Patrick says Dzhokhar Tsarnaev appears to be incapable of answering police questions because of a gunshot wound to the back of his neck.
During an interview Sunday with ABC's This Week, Boston Mayor Tom Menino said authorities may never be able to question the suspect.
Menino said Tsarnaev, 19, is in "very serious" condition, "and we don't know if we'll ever be able to question the individual."
Tsarnaev is at Boston's Beth Israel Deaconess Medical Center, where 11 victims of the bombing are still being treated.
Three marathon spectators, including an eight-year-old boy, died in a blast near the finish line of the race last Monday, while more than 170 others were injured.
Massachusetts State Police released a video on Sunday purporting to show the suspect's hiding place shortly before he was taken into custody on Friday.
The video, taken from a helicopter hovering over a residential area, shows thermal imaging camera images of a covered boat containing a glowing white mass which police claimed to be Tsarnaev.
The date and time code on the material indicates that it was shot on Friday at 19:22 local time (23:22 GMT).
Following the Boston bombing, in which two explosive devices were detonated, authorities said Dzhokhar Tsarnaev and his alleged co-conspirator and brother, Tamerlan Tsarnaev, 26, killed a police officer near the Massachusetts Institute of Technology on Thursday night, before stealing a vehicle and heading to Watertown, to the east of Boston, where a police officer spotted them.
The brothers, one in the stolen car, the other in a second car, jumped out of the vehicles and started shooting at the lone officer even as backup rushed to the scene, said Watertown Police officials.
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The suspects allegedly tossed grenades and Tamerlan Tsarnaev got within three metres of officers involved in the shootout before he ran out of ammunition and was tackled.
His injured younger brother fled and eluded the officers leading to an area lockdown with police and armed forces searching from house to house in Watertown.
Dzhokhar Tsarnaev evaded the army of search teams, and as night fell authorities scaled back the hunt.
Mass transit was allowed to resume, and people were told they could leave their homes.
Then, according to police a resident was checking the boat in his yard on Friday evening and noticed the straps weren't the way he left them.
He looked in the boat, saw blood and someone huddled in a corner and quickly called police.
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The discovery set up the final confrontation and led to the capture of the younger Tsarnaev brother.
Officers were taking no chances as they approached the boat.
In the video handout, an armoured vehicle is seen equipped with an arm which pulls back the tarpaulin covering the vessel.
Toward the end of the footage small explosions on the front of the boat are visible, believed to be flash-bang grenades used by the police to stun and disorientate Tsarnaev.
Authorities said that they attempted to talk the suspect, already weakened by a gunshot wound received some 20 hours earlier, into getting out of the boat but the suspect exchanged gunfire with law enforcement for an hour before being captured and taken away to hospital in an ambulance.
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Prosecutors haven't said yet what charges Tsarnaev will face. The naturalized American citizen from Cambridge, Mass., could be charged with using a weapon of mass destruction to kill people.
"Well, certainly charges will come soon and they will almost certainly be both federal and state-level charges — state murder charges and federal terrorism charges," CBC's David Commons reported from Boston on Sunday."
"We understand that those would have to be imminent. The FBI is expected to make an announcement at some point today, but we also expect the suspect will be appointed a federal public defender, and in a case like this, although it is extremely rare, the federal government could seek the death penalty."
Massachusetts does not have a state death penalty statute.
Members of a religious group, meanwhile, plan to gather at the corner of Boylston and Berkeley streets in Boston at 12:30 p.m. ET Sunday for an interfaith service to remember victims of the marathon bombing. Three spectators, including an eight-year-old boy, died in a blast near the finish line of the race last Monday, while more than 170 others were injured.