Jurors in the Boston Marathon bombing trial were presented on Wednesday with the home-made bombs that bombing suspect Dzhokhar Tsarnaev and his deceased brother allegedly threw at police who were searching for them in a manhunt.

The 21-year-old suspected terrorist is facing 30 charges and the death penalty for his role in the Boston Marathon attack, which killed three people and injured 264 others on April 15, 2013. According to his defense team, Tsarnaev participated in the bombing when he was 19 years old because he was dominated and motivated by his his older brother, Tamerlan, 26, who died three days after the bombing during a shootout with police.

Massachusetts State Police Trooper and bomb squad member Robert McCarthy took the stand on Wednesday, telling the jury that he heard repeated calls over the radio about the brothers "throwing bombs at us."

"We heard what we believed to be some type of explosive and saw smoke in the street lamps," McCarthy said, according to ABC News.

After the shooting, McCarthy said he found "potential pipe bombs in the middle of the road."

Jurors were also presented with two unexploded pipe bombs. McCarthy described one as being "very heavy" and full of explosive powder.

"It's basically [a pipe] elbow, approximately two inches in diameter. It still has one end-cap on it and one end-cap removed," he said, noting that the devices resemble "improvised grenades," because "it won't roll away. It will land and stop."

The second device the jury saw was straight, but also "full" of explosive powder. "This pipe is also lined with BBs," said McCarthy.

On Tuesday, Tsarnaev's former best friend testified in court today that he gave the accused a gun that was later used in the shooting death of an MIT police officer, reports ABC News.

Stephen Silva, 21, who is currently serving prison time for drug distribution and possessing a firearm, said that he gave Tsarnaev the gun because he told him that he wanted to use it in a robbery. Two months later, the brothers used the same gun to kill MIT Police Officer Sean Collier, according to prosecutors.

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