BOSTON (CBS) – Dzhokhar Tsarnaev remains the only one on trial, but his extended and dysfunctional family was once again the focus in federal court on Tuesday.

A family friend, Mirre Kuznetsov, testified how she was surprised when Tsarnaev’s mother Zubeidat started wearing a headscarf and talking intensely about her religion. Kuznetsov told jurors how she was scared when Tamerlan Tsarnaev grew his beard, saying he reminded her of a terrorist.

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The psychiatrist who treated Anzor Tsarnaev, Dr. Alexander Niss, told the jury how the Tsarnaev’s father was “a very sick man” who suffered from paranoia, depression, anxiety, and post traumatic stress disorder. Niss says Anzor Tsarnaev’s troubles stemmed his tortured upbringing in his homeland.

Jurors also heard from Michael Reynolds, a Princeton University professor whose area of study includes Chechnya. He testified about the history of the region, and the long struggles of the Chechen people. Reynolds’ testimony also reiterated what jurors have already heard: that under Chechen social codes, an older brother, like Tamerlan, can have huge power over his entire family – particularly when the father becomes ill, as was the case with Anzor.

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But under cross examination, Assistant U.S. Attorney Bill Weinreb got Reynolds to admit those social rules can be flexible, especially when a family moves away from their native land. Weinreb also made sure jurors heard that neither Anzor, Zubeidat, Tamerlan nor Dzhokhar ever stepped foot in Chechnya, even though they identified as Chechens.

When testimony did focus on the convicted bomber, it came from more people who knew him in high school, who, like those who came before them during this phase of the trial, called the 21-year-old kind and polite.

Elizabeth Zamparelli, a former Cambridge Rindge and Latin school classmate, told jurors that after she and her friends learned Tsarnaev was the Boston Marathon bomber, “we thought it was a joke, the idea that it could be him.”

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Henry Alvarez, one of Dzhokhar’s teammates from the Cambridge Rindge and Latin School wrestling team echoed that thought, testifying: “I honestly never would have imagined he could do something like this.”