Defense lawyers are trying to convince jurors the convicted Boston Marathon bomber came from a dysfunctional family.

As the penalty phase of the trial continued Tuesday, a psychiatrist who treated Dzhokhar Tsarnaev's father testified that Anzor Tsarnaev suffered from post-traumatic stress disorder. The doctor said the father claimed to have been tortured by Russians during the Chechen war and believed he was being followed by Russian spies.

A Princeton University professor testified the father's mental state led to Dzhokhar being more subservient to his older brother.

The jury is deciding whether Dzhokhar Tsarnaev should get the death penalty or life in prison for his role in the April 2013 bombing.

The jury also heard testimony from a former roommate of Tamerlan Tsarnaev's  wife who said Dzhokhar's older brother was a controlling boyfriend. The defense is trying to make the case Tamerlan was the driving force behind the bombing.