A Dartmouth College sorority and two members of a fraternity are facing charges connected to the death of a student who drowned after attending an off-campus party last summer in which alcohol was allegedly served to underage students.

The authorities in Hanover, N.H., where the elite Ivy League college is based, launched an investigation on July 7 after Won Jang’s body was recovered from the Connecticut River.

On Friday, Charles B. Dennis, chief of police of the Hanover Police Department, issued a statement announcing that Alpha Phi sorority has been charged with one count of facilitating an underage alcohol house. Two members of Beta Alpha Omega fraternity were charged with providing alcohol to a person under 21.

An autopsy found that Jang’s cause of death was drowning. He had a blood alcohol level of 0.167, according to the autopsy report.

According to police, several students decided to swim in the river after attending the party, which was hosted at an apartment rented by members of the Alpha Phi sorority.

As the group was swimming in the river, a heavy rainstorm struck the area. The students left the river in groups. No one noticed that Jang was unaccounted for.

His family told authorities that he could not swim.

According to police, most of those who attended the party, including Jang, were under 21. Alcoholic beverages were allegedly provided to the underage students by the fraternity members who were of legal drinking age.

Jang, 20, was a member of the Beta Alpha Omega fraternity, police said.

On its website, the fraternity describes itself as a “tight-knit brotherhood consisting of a broad group of students” with interests including tennis, rowing, cross country, track and field, swimming, diving and sailing.

Alpha Phi - a sorority with chapters across the United States - did not immediately respond to requests for comment.

The sorority and fraternity were suspended by Dartmouth immediately after Jang’s death, and the college launched an internal investigation, which is still underway, Jana Barnello, the college’s media relations director, said in an email.

In a statement, Dartmouth said that it “has long valued the contributions that Greek organizations bring to the student experience, when they are operating within their stated values and standards.”

“These organizations, as well as all Dartmouth students and community members, have a responsibility to ensure Dartmouth remains a safe, respectful, equitable, and inclusive community for students, faculty, and staff,” the college added.

In an email to students at the time of his death, Dartmouth’s then-dean of the college, Scott Brown, described Jang, a biomedical engineering major from Middletown, Del., as someone who “wholeheartedly embraced opportunities at Dartmouth to pursue his academic and personal passions.”

In a message sent to students on Thursday, the college said it had improved lighting and signage around its swimming docks since the incident, and security staff are patrolling the area, particularly at night. The college is also offering free swimming lessons to students and plans to review its alcohol management program.