BOSTON » For the first time since his trial began four months ago, Boston Marathon bomber Dzhokhar Tsarnaev dropped his blank, impassive demeanor and showed emotion as his Russian aunt sobbed uncontrollably and had to leave the witness stand.

Tsarnaev, 21, grabbed a tissue and repeatedly dabbed his eyes and cheeks while his aunt became so upset that she was unable to testify on his behalf as his lawyers try to persuade a federal jury to spare his life.

Tsarnaev had maintained an uninterested expression since his trial began in January, most of the time staring straight ahead and only occasionally glancing over at witnesses, including people who lost loved ones in the 2013 bombing.

His aunt, Patimat Suleimanova, cried as she sat down about 10 feet from Tsarnaev. She was only able to answer questions about her name, her year of birth and where she was born before she stepped down from the witness stand after she was unable to compose herself.

Five Russian relatives — three cousins and two aunts — took the witness stand for the defense. As Tsarnaev was led out of the courtroom before the lunch recess, he blew a kiss at the other aunt, who also cried during her testimony. The relatives all acknowledged they had not seen Tsarnaev since he was 8, when he moved to the U.S. with his family.

Testimony is scheduled to resume Tuesday.

Tsarnaev, who had lived in the former Soviet republic of Kyrgyzstan and the Dagestan region of Russia, was convicted last month of 30 federal charges in the bombings, including 17 that carry the possibility of the death penalty. He moved to the U.S. in 2002 and committed the bombings, which killed three people and wounded 260 others, when he was 19.

Prosecutors say Tsarnaev and his radicalized older brother, Tamerlan, were equal partners in the bombing, and they have urged a jury to sentence Tsarnaev to death.

Tsarnaev’s lawyers say Tamerlan, 26, was the mastermind of the attack and lured his brother into his plan. Tamerlan died days after the bombings following a shootout with police.

A cousin testified Monday that Dzhokhar was a kind and warm child, so gentle that he once cried while watching “The Lion King.”

“I think that his kindness made everybody around him kind,” Raisat Suleimanova said through a Russian translator.

Assistant U.S. Attorney William Weinreb pounced, asking her if she believes a deadly attack on innocent civilians can be considered kind. Tsarnaev’s lawyer objected, and Suleimanova was not allowed to answer the question.

Another cousin, Nabisat Suleimanova, said Dzhokhar was loved by the entire family. “He was an unusual child. He was wunderkind,” she said.

She said Dzhokhar had a softening effect on an aunt who was very stern and strict with her own children, but not with Dzhokhar.