NEW YORK (CBSNewYork) -- We're learning more about the Boston Marathon bombing suspect killed in a shootout with police.
Not everyone is surprised to learn Tamerlan Tsarnaev was one of the suspects in the bombings.
As federal investigators search for a possible motive, a clearer picture has emerged about Tsarnaev, the older brother in the alleged plot that stunned the the world. Entertainment Tonight's Rob Marciano uncovered exclusively a boxing documentary that shows the alleged Boston bomber in 2010.
On Monday, for the first time, the public got to hear his voice.
On the video, Tsarnaev looks into the camera, cocky, smiling and ready to fight.
"He's a machine. A clean, clear, technique, knows what he needs to do and just does it," trainer John Allen said.
Allen was Tamerlan's trainer. They worked out at Wai Kru in Allston, Mass. He said Tsarnaev was the best in New England, with dreams of going to the Olympics.
But in 2010 Tamerlan was disqualified from competition for not being a U.S. citizen. Also weighing heavily was a pending domestic violence charge, Marciano reported.
When asked out the charge, Allen told Marciano, "He kept it from me. He gave me the impression that the reason he unable to go to the Olympics was because he couldn't become a citizen, because of mishandling of paperwork. He felt that it was done on purpose so that the guy he beat could go to the Olympic trials."
Marciano: "Do you think that this road block in his boxing career set him on the wrong path, set him on the path to these bombings?
Allen told Marciano he was shocked when he found out Tamerlan was the one suspected of the bombings, but not everyone in the gym was.
Marciano: "Do you believe at any time when you knew Tamerlan that he could be a terrorist?"
Allen: "No, but I will say there were a couple of members who thought that he might be."
Marciano: "What did they say?"
Allen: "Well, it's when he began to actually pray, face towards Mecca and pray. Right away you heard comments: 'This guy a terrorist? I think this guy's a terrorist.'"
DZHOKHAR APPEARS IN VIDEO WITH BROTHER'S DAUGHTER
Video of surviving bombing suspect Dzhokhar Tsarnaev has also surfaced. As CBS 2's Jessica Schneider reported Monday night, a YouTube video from March showed him joking around with his brother's young daughter.
"Give me a kiss!" he tells the little girl.
Meanwhile, female DNA was found on a fragment from one of the Boston Marathon bombs. Sources told CBS News the DNA could have come from a spectator, a clerk who sold the bomb materials, or a female accomplice.
On Monday, FBI agents were at the Rhode Island home where Tamerlan Tsarnaev's widow was staying. Katherine Russell submitted a DNA sample, but she is not considered a suspect, officials said.
Also Monday, the suspects' mother, Zubeidat Tsarnaeva, said she hopes to come to the United States to see her surviving son – even though she has pending shoplifting charges against her in Massachusetts.
The father of the suspects, Anzor Tsarnaev, had been planning to fly to the United States, but his trip is now postponed due to illness.
Dzhokhar Tsarnev is in a 10-foot-by-10-foot cell with a steel odor and a food slot. A prison spokesman said he is under extra surveillance and has been interacting with staff.
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