Authorities are investigating whether the cornered Boston bombing suspect arrested in Watertown, Mass., Friday tried to commit suicide as cops closed in, reports today said.

Dzhokhar Tsarnaev, 19, remains under guard at a hospital with serious injuries and has been unable to speak to interrogators — and today Boston’s mayor said it’s possible the terror suspect may never be able to be questioned.

CBS correspondent John Miller reported that one of the wounds Tsarnaev suffered was a bullet wound to the back of the neck, and that authorities think he may have tried to kill himself rather than be captured.

“But [investigators are] saying that wound to the back of the neck is very possibly a suicide attempt. They say it appears from the wound that he might have stuck a gun in his mouth, and fired and actually just went out the back of his neck without killing him,” Miller reported.

Tasrnaev fired several shots from inside the boat, but investigators don’t know in which direction he fired, Boston Police Commissioner Ed Davis said today.

Tsarnaev was captured Friday after being pulled bloody and wounded from a tarp-covered boat in Watertown, a suburb of Boston, after a massive manhunt that involved door-to-door searches.

Police believe Tsarnaev and his older brother Tamerlan, who was killed in a shootout with police, planned more attacks, Davis said. Authorities say they found an arsenal of homemade explosives after a gun battle between police and the suspects in the Boston suburb of Watertown early Friday.

“We have reason to believe, based upon the evidence that was found at that scene — the explosions, the explosive ordnance that was unexploded and the firepower that they had — that they were going to attack other individuals,” Davis said. “That’s my belief at this point.”

Dzhokhar Tsarnaev could be charged as early as Sunday, although it was not clear what those charges would be. The twin bombings killed three people and wounded more than 180.

The most serious charge available to federal prosecutors would be the use of a weapon of mass destruction to kill people, which carries a possible death sentence. Massachusetts does not have the death penalty.

Boston Mayor Thomas Menino said today he hopes federal authorities “throw the book at him.” He also said it appears the alleged bombers acted alone.

Also today, Massachusetts Gov. Deval Patrick said “chilling” surveillance video from the Boston Marathon attack shows one suspect dropping his backpack and calmly walking away from it before the bomb inside exploded.

The video clearly puts 19-year-old Dzhokhar Tsarnaev at the scene of the attack, Patrick said on NBC’s “Meet the Press.”

“It does seem to be pretty clear that this suspect took the backpack off, put it down, did not react when the first explosion went off and then moved away from the backpack in time for the second explosion,” Patrick said. “It’s pretty clear about his involvement and pretty chilling, frankly.”

Patrick said he hadn’t viewed the videotape but had been briefed by law enforcement officials about it.

Investigators have determined the bombs were fashioned from pressure cookers packed with explosives, nails and ball bearings and hidden in black backpacks.