LOS ANGELES — Authorities dropped an investigation into a reported sexual assault at Hugh Hefner’s Playboy Mansion because of insufficient evidence, prosecutors said Friday.

The case was submitted to county prosecutors, and no charges will be filed, the Los Angeles Police Department said in a statement.

The investigation was launched Monday into claims that a 22-year-old woman might have been raped while unconscious, officials said. The allegation involved a 17-year-old boy.

“She recalls at one point having sexual intercourse with the minor and pushing him away,” said Sandi Gibbons, a district attorney’s spokeswoman.

Authorities could not corroborate the woman’s statement, Gibbons said. The woman also has claimed memory loss and declined to pursue the case, officials said.

Rob Hilburger, West Coast publicity director for Playboy Enterprises, said police told the company Friday that the investigation had ended.

“Safety and security at the mansion remain a priority, not only for those who live there, but for all invited guests,” Hilburger said. “We thank the LAPD for their quick and thorough investigation into this matter.”

The Playboy Mansion is in the wealthy Holmby Hills area of West Los Angeles.