Manslaughter plea in 2009 Harvard shooting

Victim’s mother speaks to court

Jason Aquino (center) and his attorney, Matthew Kamholtz, listened to Superior Court Judge Howard Whitehead in Middlesex Superior Court in Woburn yesterday. Aquino will serve 18 to 20 years for the shooting of Justin D. Cosby in a Harvard dormitory. (Kayana Szymczak for The Boston Globe)

A New York man pleaded guilty yesterday to manslaughter, admitting he participated in the fatal shooting of a Cambridge man inside a Harvard University residence hall in 2009.

Jason Aquino, 21, pleaded guilty to manslaughter, armed robbery, and misleading a grand jury in Middlesex Superior Court. The mother of the victim, Justin D. Cosby, 21, scolded him for his role in her son’s slaying.

Aquino, under a deal with Middlesex prosecutors, will serve 18 to 20 years in state prison for all three charges. The time is to be served concurrently.

Denise Cosby, who has attended multiple court hearings since the killing of her son, delivered a victim impact statement denouncing Aquino and recalling her son with a mother’s love.

“I sit here and look into the face of what is supposed to be a man,’’ Cosby said in a stern voice. “You are a fool.’’

Aquino is one of three New York City men who came to Cambridge on May 18, 2009, and were intent on robbing Justin Cosby of marijuana and cash. Cosby was shot while all four men were inside an entry to Harvard’s Kirkland residency hall when Cosby refused to hand over what authorities called a substantial amount of marijuana.

“You lured my son to his death,’’ Cosby told Aquino. “My heart sinks, and every fiber of my body aches. When you killed my son, you killed a part of me.’’

The alleged shooter and mastermind of the drug rip-off plan, Jabrai Jordan Copney, 22, is scheduled to go on trial for first-degree murder April 4. Copney has pleaded not guilty.

The third man, Blayn Jiggetts, 21, has agreed to testify against Copney in return for pleading guilty to manslaughter and a prison term of less than 20 years.

The New York men gained access to the secure dormitory from Brittany Smith, 24, Copney’s girlfriend and a Harvard senior just one week from graduation, authorities said. Smith is also accused of stashing the murder weapon in a friend’s room at another Harvard dorm.

Smith, of New York City, was indicted by a Middlesex Superior Court grand jury on March 16 on charges of illegal possession of a firearm, accessory after the fact to murder, willfully misleading a grand jury, and willfully misleading a police officer, according to the office of the Middlesex district attorney.

Smith’s longtime friend Chanequa Campbell, who was also a Harvard senior, has testified that she knew the men were coming to the campus and that she knew Jiggetts would be armed with a handgun.

“Today, Jason Aquino is held accountable for his part in the killing of Justin Cosby, by admitting the role he played and his culpability in the shooting death of this young man, which occurred in broad daylight on the campus of one of the world’s premier educational institutions,’’ Middlesex District Attorney Gerard T. Leone Jr. said. “With this defendant’s admission, we now move forward with our prosecution against the man we alleged shot the victim, and [against] the remaining coconspirators.’’

Yesterday, Aquino showed up in court wearing jeans and a long-sleeved, blue-collared shirt. Aquino has been held without bail since his arrest in 2009, and only his court-appointed attorney, Matthew Kamholtz, appeared on Aquino’s behalf.

Aquino, who is short and slight, answered a series of routine legal questions posed by Superior Court Judge Howard Whitehead, but he did not otherwise speak.

At one point in the investigation, Aquino’s attorneys had negotiated a deal where he faced a maximum of five years’ imprisonment as an accessory after the fact.

But Middlesex prosecutor Daniel Bennett said in court that deal was pulled off the table when it was shown that Aquino had lied under oath.

Before Cosby entered the dorm, he met Copney and Aquino on a Cambridge street and only then agreed to complete the deal inside the dorm, Bennett said.

Aquino did not tell authorities about participating in that meeting.

When Cosby delivered her victim impact statement, Aquino sat with his head turned down and away from the Cambridge woman, who was sitting in the witness box as she spoke.

“He was full of charisma, promise and hope. Justin loved life,’’ she said of her son, the younger of her two children. “My son just meant the world to me. He had a smile that was infectious.’’

Cosby recalled rushing to the hospital the night her son was shot and watching him slowly slip away because doctors could not halt the bleeding caused by a bullet that pierced his stomach.

She spoke of seeing her son die, seeing her son in a casket, and then walking away from the cemetery after his burial, “leaving my son in a dark, cold grave.’’

Cosby said she had hoped that all three men charged in the case would be given the maximum sentence of life imprisonment without parole.

“What Justin did may have been illegal, but what you did was immoral,’’ she told Aquino.

She said she has grudgingly approved the plea agreements in part because of her faith in God.

“I believe in a higher power and a higher court,’’ she said. “Ultimately, you will pay to the judge of all judges, the courts of all courts.’’

Aquino will be formally sentenced May 2, after the Copney trial.