He had distributed fliers for a casting call, one finding its way to a bulletin board at the University of Michigan, where Pamela Guest was then a senior. At the audition, in an apartment on the outskirts of Ann Arbor, the man told her that she was perfect for the part.

There was a bare mattress on the floor of one room, but a woman had let her in, putting Ms. Guest at ease. The man said he had written a famous advertising jingle for Maxwell House coffee, and that this could be her lucky break — if she was brave enough to read the part without her clothes on.

She did so. Then, Ms. Guest said in an interview last week, he raped her.

For more than 40 years, Ms. Guest has kept the memory of that afternoon a secret, too ashamed then to report the rape, too pained now to recount it to any but a trusted few. But now a sensational, high-profile and unrelated crime has not only resurrected her experience of the attack — it has also given her an idea of who raped her.

So it was that Ms. Guest found herself sitting in a courthouse in Manhattan recently, attending the murder trial of a man she had never met. The man on trial, Nicholas Brooks, is accused of killing his girlfriend, a fashion designer named Sylvie Cachay, who was found submerged in a bathtub in the elite Soho House in December 2010.