(CNN) -- Boston marathon bombing suspect Dzhokhar Tsarnaev suffered multiple and severe gunshot injuries before his capture in April, newly released court documents show.
The most serious of the injuries was a gunshot wound that appeared to enter through the left inside of his mouth and exit through the lower left side of his face, said Stephen Ray Odom, a trauma surgeon who treated Tsarnaev at Beth Israel Deaconess Medical Center.
"This was a high-powered injury that has resulted in skull-base fracture, with injuries to the middle ear, the skull base, ... his ... vertebrae ... as well as injury to the pharynx, (and) the mouth." Odom said in testimony given April 22, three days after Tsarnaev was arrested following the bombing.
His testimony, unsealed Monday, does not say whether the 20-year-old college student inflicted the wound on himself or suffered it during his showdown with police April 19.
Authorities cornered him in a boat in the backyard of a Watertown, Massachusetts, home after an intense manhunt.
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Another document unsealed Monday said a special team of federal agents were able to speak with the seriously wounded Tsarnaev for about two days without any Miranda warnings being given, under a "public safety exception." The document shows he was read his Miranda rights in the hospital on April 22.
Tsarnaev is charged with killing four people -- three spectators who died in the April 15 bombings and a Massachusetts Institute of Technology police officer ambushed in his cruiser a few days later.
At least 264 people were wounded in the double bombings, which took place near the marathon finish line.
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He is awaiting trial, after having pleaded not guilty to 30 federal charges. If convicted, he could receive up to life in prison or the death penalty.
His older brother, Tamerlan, is also accused of the attacks. He was killed when Tsarnaev ran over him as police were trying to handcuff him, authorities said.
CNN learned in the weeks following the bombing that Tsarnaev admitted to the acts, and said he and his brother acted alone. Sources say he has since stopped talking with the government.
Tsarnaev pleads not guilty.
CNN's Lizzie Jury contributed to this report.