Prosecutors offered no explanation as to what they found during their investigation or why the case has been dropped. No charges were ever filed against Copperfield. Representatives for the magician have alleged that the woman was untruthful, and that he never forced himself on her.
"We filed a notice today that we had terminated the grand jury inquiry,” Emily Langlie, a U.S. Attorney's Office spokeswoman, tells PEOPLE.
The victim, who was 21 during the encounter, also has a lawsuit against the magician, which was filed last July and put on hold two months ago to allow the criminal investigation to run its course.
The investigation went public over two years ago, when law enforcement officials conducted searches at Copperfield's property warehouse and magic museum in Las Vegas.