A Harvard graduate student charged with the murder of a local teenager pleaded not guilty yesterday before a packed Cambridge courtroom.

Alexander Pring-Wilson, 25, stood silently through the five-minute arraignment hearing at the Cambridge District Court, as the family of victim Michael Colono looked on in tears.

Pring-Wilson, a student at the Davis Center for Russian and Eurasian Studies, was accused of stabbing Colono in an early morning altercation Saturday, outside a local pizza parlor. Colono later died of his wounds.

Jeffrey Denner, Pring-Wilson’s attorney, requested that his client receive medical and psychological evaluations and a polygraph test before a bail hearing. A judge agreed to Denner’s request and said she will set bail on Friday.

Outside the courtroom, Denner said that his client stabbed Colono in self-defense after he was “attacked and assaulted.”

Denner said that the polygraph test will establish that his client can be safely released on bail.

The victim’s family—about 20 members of which attended the hearing—angrily denied that Colono initiated the altercation. During the hearing, one interjected with a cry of “bullshit” as Denner requested the medical evaluations.

Pring-Wilson entered a not-guilty plea against the current charge of murder, but Denner said the prosecution has the option of indicting him with a lesser charge.

According to investigators’ accounts, released Saturday by District Attorney Martha Coakley, Pring-Wilson was walking home from a nightclub alone sometime after 1 a.m. when he encountered Colono, 18, sitting in a car with his cousin and his cousin’s girlfriend.

They say Colono got out of the car, and a violent fight between he and Pring-Wilson ensued, leaving Colono with five stab wounds to the torso.

Emily LaGrassa, the Middlesex County District Attorney spokesperson, said Colono and friends left the scene not realizing he had been stabbed. Colono was pronounced dead at the Beth Israel Deaconess Medical Center later that night.

Pring-Wilson, whom police had questioned and released at the scene, was later arrested.

Officials said Saturday that they had not recovered a weapon, but Denner said that his client had defended himself using a pocket knife with a three inch blade.

LaGrassa said today that she could not release further details about the investigation.

Pring-Wilson, a Colorado native, planned to receive his Master’s degree this spring, and then return to Colorado for law school.