A Missouri woman accused of posing as a teenage boy on the Internet and harassing a 13-year-old girl who later committed suicide, pleaded not guilty in a federal court here Monday morning to charges of Internet fraud and conspiracy to inflict emotional distress.

In May, a grand jury indicted the woman, Lori Drew, 49, under the federal Computer Fraud and Abuse Act, used in cases in which hackers gain access to information stored on protected computers. It is the first time that statute will be used in a social networking case, according to the United States attorney for Los Angeles, Thomas P. O’Brien.

Ms. Drew is accused of setting up a false account on MySpace, the social networking site, which is based in Beverly Hills, calling herself Josh Evans and, along with other people, sending cruel messages to the 13-year-old, Megan Meier. Megan was a neighbor in a St. Louis suburb, O’Fallon, who had at one time been friends with Ms. Drew’s daughter.

The last message from “Josh,” in October 2006, told Megan that “the world would be a better place” without her. Megan hanged herself in her bedroom closet later that day.

Ms. Drew sat quietly in the courtroom Monday before entering her plea in front of Magistrate Judge Paul L. Abrams. Her lawyer, H. Dean Steward, told reporters she would have no comment.

Magistrate Abrams set bail for Ms. Drew at $20,000 bail. She was allowed to return to Missouri until trial, which was scheduled for June 29, said Mark Krause, the assistant United States attorney.