Dzhokhar Tsarnaev is communicating with authorities through writing, an official said. (Creative Commons)

Officials did not reveal what questions they asked Dzhokhar Tsarnaev, but said the 19-year-old is recuperating from a bullet wound in the neck that rendered him unable to speak. Tsarnaev was in serious condition Sunday, two days after authorities found him in a tarp-covered boat in a Watertown backyard. 

SEE ALSO: Boston Suspect Unable To Speak To Authorities

Investigators waiting to interrogate Tsarnaev are looking into the possibility that the wound in his neck was self inflicted. An official said it will take "some time" before agents can review information held by Russian authorities that led the Russian government to ask the FBI to review the activities of Tamerlan Tsarnaev, the older brother killed in a gunfight with police, according to USA Today.

Tamerlan Tsarnaev's six-month trip to Russia last year has also drawn scrutiny as officials are wondering if he returned with more extreme political and religious views. The brothers' parents have insisted that Tamerlan's visit to Dagestan and Chechnya last year were to see relatives and had nothing to do with militants.

U.S. Attorney Carmen Ortiz was preparing criminal charges, but it was not clear when charges would be filed, according to Reuters. No news conference or announcement was planned on Sunday.

SEE ALSO: Boston Bombing Suspect Denied Miranda Rights, May Go To Guantanamo

The suspect was being watched by armed guards in the intensive care unit of Beth Israel Deaconess Medical Center, where the older brother was pronounced dead on Friday. The twin bombings on April 15 killed three people and injured more than 170 near the finish line of the Boston Marathon.

Read more Neon Tommy stories on the Boston Marathon bombings here.

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