Cammy Duong woke up in a Manhattan hotel room in July 2017 and, dazed, called a friend she was supposed to meet later that morning: “I think I was raped,” she said, crying.

The police investigation lasted months. But when the case reached the Manhattan district attorney’s office, prosecutors quickly declined to bring charges, records show. It would be seven more months before Ms. Duong got an explanation.

“I remember leaving and crying and feeling helpless,” said Ms. Duong, now 32. “I felt like nobody believed me.”

The Me Too movement led to heightened awareness of the prevalence of sexual assault, an increase in reports to police, and a new hope that people accused would be more frequently held accountable. But in New York City, statistics and the accounts of women who say they were attacked suggest that little has changed about the way the criminal justice system grapples with rape accusations.