Nantucket prosecutors have dropped a sexual assault case against actor Kevin Spacey, citing the “unavailability” of the complaining witness.

Spacey had been accused of groping an 18-year-old busboy at the Club Car restaurant in July 2016. He was charged with indecent sexual assault, and a trial was set to be held in the fall.

However, the case has been teetering on the brink of dismissal since an evidentiary hearing last week, during which the accuser invoked his Fifth Amendment rights.

Spacey’s attorney, Alan Jackson, had sought access to a phone which contained texts from the evening of the alleged incident. The accuser has said that the phone is missing.

Investigators had scanned the phone and returned it to the accuser in December 2017. Jackson alleged that the accuser and his mother had manipulated text messages on the phone, and asked at the hearing whether the accuser was aware that manipulating evidence is a crime. After a recess, the accuser’s attorneys said that he would not answer additional questions.

The young man had sued Spacey in civil court last month. His attorney, Mitchell Garabedian, dropped the suit a week later without giving an explanation. Garabedian later told local media that the dismissal was not the result of a settlement.

“My client and his family have shown an enormous amount of courage under difficult circumstances,” Garabedian said in a statement on Wednesday.

Spacey still faces a criminal investigation in Los Angeles and another in London. Scotland Yard recently questioned the actor on allegations from six individuals, dating from 1996 to 2013. The Los Angeles County District Attorney’s office declined to prosecute yet another case, from 1992, last year, citing the statute of limitations.

A massage therapist has also sued Spacey in federal court in Los Angeles, accusing Spacey of trying to kiss him and forcing him to touch Spacey’s genitals during a session in October 2016. That case remains pending.

In a statement on Wednesday, the Cape and Islands District Attorney’s office said it met with the Club Car accuser on Sunday to discuss the status of the case.

“The complaining witness was informed that if he chose to continue to invoke his Fifth Amendment right, the case would not be able to go forward,” the office said. “After a further period of reflection privately with his lawyer, the complaining witness elected not to waive his right under the Fifth Amendment.”

The only other avenue, the D.A.’s office said, would have been to grant the accuser immunity from prosecution and then force him to give testimony. However, the office stated that that approach would damage the accuser’s credibility, making a prosecution untenable.