During a rap concert on the Dartmouth campus in October 2009, Alexi Pappas, dressed in a full-body leotard and sitting in the front row, was called on stage to dance.

Ms. Pappas, then a sophomore on the school’s cross-country team and a member of the Dog Day Players, an on-campus improvisational theater group, accepted the invitation.

As Ms. Pappas began to dance and the decibel level began to rise, Jeremy Teicher, a senior and aspiring filmmaker who was on stage covering the event as a photographer, trained his lens on Ms. Pappas.

“I couldn’t look away,” he said. “I was just thrown by her beauty.”

Mr. Teicher soon began asking around about the girl whose image he could not get out of his mind.