MOSCOW, March 12 (RAPSI) – A witness in the criminal case against Dzhokhar Tsarnaev over Boston Marathon bombings in 2013 told the court that he saw the accused at the scene of Massachusetts Institute of Technology (MIT) Police Officer murder, CNN reports on Thursday.

Nathan Harman, MIT mathematics Ph.D. candidate who was cycling through the area on the day of MIT policeman Sean Collier’s murder, claimed that he saw a person leaning into the officer's squad car, a person he identified at court as Dzhokhar Tsarnaev, CNN reports.

Prosecutors showed a video footage from the scene showing an encounter between Collier and his assailants although it’s not clear who or how many people were present at the scene.

Prosecution claims that Tsarnaev brothers attacked Collier in order to get his gun, CNN reported.

On the afternoon of April 15, 2013, two explosions occurred near the finish line of the Boston Marathon. IEDs devised from pressure cookers, low explosive powder, shrapnel, adhesive, and other materials were hidden in backpacks that were then placed near metal barricades in areas packed with hundreds of spectators.

Tsarnaev was arrested following a dramatic manhunt during which his brother and co-suspect Tamerlan was killed, as was MIT Police Officer Sean Collier. Tsarnaev was charged on April 21 with the use of a weapon of mass destruction and malicious destruction of property resulting in death.

US prosecutors filed their notice of intent to pursue the death penalty against Tsarnaev on January 30, 2014. The government is seeking the death penalty for the accused.

Tsarnaev has pleaded not guilty to 30 criminal counts.