(CNN) Four men pleaded guilty Monday in connection with a 2013 fraternity hazing death of a New York college student.

Baruch College freshman Chun "Michael" Deng, 18, died from his injuries after fraternity brothers waited to contact authorities when Deng was unconscious as a result of a fraternity ritual on a group trip to the Poconos in Pennsylvania, according to court documents.

Kenny Kwan, 28, Charles Lai, 26, Raymond Lam, 23, and Sheldon Wong, 24, pleaded guilty to charges of voluntary manslaughter as accomplices and hindering apprehension for concealing evidence, according to the Monroe County District Attorney's Office. The four men were originally charged with murder.

More than 30 other fraternity members are awaiting court proceedings in connection with the death after a Monroe County, Pennsylvania, grand jury recommended charges. The fraternity, Pi Delta Psi, is also charged with murder, and is scheduled to begin trial this November, according to court documents.

"It's a long time coming. We've had this case now for almost three full years," Monroe County Assistant District Attorney Kimberly Metzger told CNN affiliate WBRE

Lam originally made bail and entered a not guilty plea in 2015 when the four were arraigned. The other three had not entered pleas.

Wong's attorney, Steven Brill, said he and his client are preparing for sentencing, which is scheduled for December.

"Sheldon accepted responsibility for his actions and the mistakes he made. Above all Michael Deng was a friend and Sheldon remains deeply saddened by his unintended death," Brill said.

CNN reached out to the attorneys for the other three men, but did not hear back.

The guilty pleas come the week after 18 men in a Penn State University fraternity were charged in connection with the death of 19-year-old freshman Timothy Piazza . Piazza died from injuries he suffered in February on the first night of pledging Beta Theta Pi, a fraternity that was supposed to be alcohol-free at Penn State, a result of a suspension eight years ago.

The death of Piazza led to one of the largest criminal indictments against a fraternity and its members in recent history. More than 1,000 counts were levied against 18 members of Beta Theta Pi, including eight who were charged with involuntary manslaughter and aggravated assault.

What happened

According to police, the Pi Delta Psi fraternity was conducting a ritual outdoors called the "glass ceiling" with new pledges.

The objective was for Deng, who was blindfolded and wearing a backpack containing a 30-pound bag of sand, to navigate toward someone calling him while other fraternity brothers physically prevented that from happening, police said.

Deng fell backward, struck his head and was immediately unconscious and unresponsive, according to police.

He was carried inside a rented house and placed by a fire because his body was cold and wet from the conditions outside, police said. Deng remained unconscious while members of the fraternity researched his symptoms online and found the closest hospital, according to an affidavit in support of the charges.

At least two hours passed before he received medical care, police said.

Forensic analysis determined the delay in treatment "significantly contributed to the death of Mr. Deng" and resulted in neurogenic shock, police said.

Three fraternity members drove Deng to a Pennsylvania hospital early in the morning, authorities said.

Victim's family says they'll fight to end frat hazing

Deng family attorney Doug Fierberg said the guilty pleas were "a long time coming."

"It has taken a few years before any of the wrongdoers took responsibility for their role in Michael's death, Michael never should have died," Fierberg said.

The family plans to pursue civil action against the charged men when criminal proceedings are over, Fierberg said. The Deng family released a statement after the guilty plea hearings.

"We wish to thank the police and prosecutors in Monroe County for their diligence in bringing these men to justice. Michael was a devoted, bright and loving son, and nothing can undo or lessen the crushing heartbreak of losing our only child to fraternity hazing. Michael's death was absolutely preventable, and our family will, now and forever, do everything in our power to hold these men and their fraternity responsible. We hope our work will contribute to ending hazing and save another family from suffering."