American University is investigating potential student misconduct after the disclosure of a string of e-mails and other documents laced with expletives and slurs and referring to assault, raucous parties and rape.

The e-mails — leaked last week through the Web site Tumblr and cited in a story in the Eagle, the campus student newspaper — appear to chronicle lewd conversations between AU students and allude to a campus “brotherhood.” The messages, which could not be immediately authenticated, include references to a group that calls itself Epsilon Iota and appear to come from a Google group of the same name.

Although there is no officially recognized Epsilon Iota fraternity at AU, the group is a known social organization on the private university’s Northwest Washington campus. AU openly discourages its students from joining.

The e-mails have sparked an uproar. An online petition drive — “No More Silence” — is demanding that the university take steps to prevent sexual assault and suspend any students involved in the e-mails, which include many crude references to women. Some of the messages date to 2012.

On Monday, AU President Cornelius M. “Neil” Kerwin said in a statement to the campus that “harmful behaviors” depicted in the e-mails “not only conflict with our values and standards, but also may represent breaches of our student conduct code and of the law.”

Kerwin pledged “swift and deliberate action” to investigate. He said AU would apply its student conduct code “to its fullest extent” and cooperate with law enforcement if any crimes are uncovered.

“This situation cannot be viewed as an isolated set of circumstances,” Kerwin said. “It raises broader concerns about student conduct and high risk and harmful behaviors. Over the ensuing weeks and months, we will review with the community the steps we have taken to educate and address such issues and solicit ideas about what else might be effective in curtailing dangerous, damaging and illegal behaviors.”

One person whose name appears on some of the e-mails that were posted said, “I can’t talk to you right now” when reached by telephone Tuesday. Another hung up when reached by telephone, and a third did not immediately return a voice-mail message. Other people whose e-mail addresses are in the string of posts did not immediately respond to e-mails seeking comment.

It is unclear whether those people actually wrote the messages, which contain private conversations and discussions across a range of subjects and documents attributed to the group. One document contains suggestions for T-shirt slogans Epsilon Iota could use as they recruit during “rush”; a string of messages discusses a fight that led to an allegation of assault; and others refer to heavy drinking and womanizing.

Epsilon Iota once signified an AU chapter of the Alpha Tau Omega national fraternity. But the national fraternity and the university withdrew recognition of the chapter 13 years ago.

Wynn R. Smiley, chief executive of Indianapolis-based Alpha Tau Omega, said Tuesday that its AU chapter was closed in 2001 because of “ongoing alcohol issues” and other concerns. ATO, Smiley said, has no connection with the organization known on campus as EI.

On Tuesday afternoon at the Kay Spiritual Life Center on campus, Kerwin fielded questions from students who were upset by the e-mails. One woman said the incident made her feel unsafe. Another pressed the university to do more to prevent sex assaults, declaring: “I am revolted, and nauseated and disgusted.”

Gail Short Hanson, AU’s vice president of campus life, said university officials share their anguish. “What a huge, huge devastating letdown for all of us,” Hanson said. She pledged a full review. “There isn’t anyone here who doesn’t feel this, at their core, let down in a horrible way.”

Scott Weathers, a junior from Chapel Hill, N.C., who was in the audience, said the administration’s reaction to the incident seemed slow. “I don’t think they fully grasped how big a deal it is,” he said. “It’s already getting such huge traction online.”