BOSTON, Massachusetts: The surviving suspect in the Boston Marathon bombings remained in serious condition in the hospital yesterday, unable to speak due to injuries to his neck and tongue sustained while on the run from police, officials said.

The US Federal Bureau of Investigation still was unable to interview Dzhokhar Tsarnaev, 19, Boston Police Commissioner Ed Davis told CBS television, and authorities may never be able to speak with him, Boston Mayor Thomas Menino said.

The suspect was in Beth Israel Deaconess Medical Center while US Attorney Carmen Ortiz, the federal prosecutor for the Boston area, was working on filing criminal charges, Davis said. An announcement on charges could come later, he said.

Tsarnaev was shot in the throat and had tongue damage, said a source close to the investigation, speaking on condition of anonymity.

“We don’t know if we’ll ever be able to question the individual,” Menino told ABC’s “This Week” program. He did not elaborate.

Tsarnaev will be defended by the Federal Public Defender Office, which had yet to issue any public statements on the case.

Investigators were seeking a motive for the Boston Marathon bombings and whether others were involved besides the ethnic Chechen brothers they suspect carried out the attacks.

Meanwhile, website used by Russia’s North Caucasus rebels denied yesterday any link to the deadly Boston Marathon bombings that have been blamed on two ethnic-Chechen suspects.

“The command of the Vilayat Dagestan mujahedeen... declares that the Caucasus fighters are not waging any military activities against the United States of America,” the Kavkazcenter.com website said.

“We are only fighting Russia, which is not only responsible for the occupation of the Caucasus, but also for monstrous crimes against Muslims,” the rebel site said.

Media reports in the United States said the FBI was studying possible links between the two main suspects — brothers Dzhokhar and Tamerlan Tsarnaev — and the Caucasus Emirate movement led by feared warlord Doku Umarov.

The Tsarnaev brothers are the main suspects in the double bomb attack on the Boston marathon, which killed three people wounded about 180. A policeman was killed and another was left fighting for his life after gunbattles during the hunt.

Governor Patrick said he hopes the teenager survives. “We have a million questions and those questions need to be answered,” he added.

Media reports say authorities did not read Tsarnaev his normal rights to see a lawyer or stay when he was captured, invoking a special exception for security reasons.

That has left US authorities facing tough decisions over how to handle the investigation and any trial.

Republican Senators John McCain and Lindsey Graham have led calls for the teenager to be declared an “enemy combatant,” which would give him the same status as Guantanamo “war on terror” detainees.

Legal rights groups have been quick to insist that he face a criminal trial, even though Tsarnaev would be likely to face a death penalty calls.

The Tsarnaev family are ethnic Chechens who moved to the United States from the former Soviet state of Kyrgyzstan around 2002.

Media reports say Tamerlan Tsarnaev became a fervent Muslim in recent years. Much focus is now being put on his six-month trip to the Russian region of Dagestan last year.

US President Barack Obama and Russian President Vladimir Putin agreed during telephone talks Saturday to increase cooperation against international terrorism, the Kremlin and White House said.

The FBI acknowledged on Friday that an unnamed foreign government, reportedly Russia, asked for information about Tamerlan Tsarnaev in 2011. The FBI interviewed the man but said it had found no “derogatory” information.

The men’s social media pages appeared to express sympathy with the struggle in Chechnya, which has been ravaged by two wars since 1994 between Russia and Islamist-leaning separatist rebels.

Dzhokhar Tsarnaev, who became a US citizen last year, was caught after a man named Dave Henneberry saw blood on boat he kept in his backyard in Watertown, in the Boston suburbs. When Henneberry lifted the tarp he saw the wounded teenager curled up inside, police said.

The University of Massachusetts student was surrounded for a showdown that included a final gunbattle before Tsarnaev surrendered to authorities.

Thermal images taken by a police helicopter overhead showed Tsarnaev slumbering in the covered boat. They also showed a robotic arm reaching to lift the cover so cameras could peek inside.

Over the weekend crowds gathered outside Henneberry’s home, craning their necks to gaze at his bullet-riddled and blood-smeared 1980s boat.

Neighbor George Pizzuto said that Henneberry was “in shock” and “totally distraught” at the events of Friday night, and is not talking to reporters.

Henneberry has gone into hiding and the boat, his prized possession, is being kept under wraps by police as they collect evidence against Tsarnaev.

Police say the brothers killed one officer and wounded another as they fled, hurling home-made bombs at their hunters.

Tamerlan Tsarnaev died in one gunbattle. His brother was also hit but escaped.

Watertown police chief Edward Deveau said the pair had at least six bombs with them when being chased and that Dzhokhar had driven over his brother as he escaped.

Fifty-eight of the victims from the bomb attack are still in Boston hospitals, with three in critical condition.