ROME — Pope Francis has accepted the resignation of an auxiliary bishop of Los Angeles, the Vatican announced on Wednesday, after an investigation into an accusation of misconduct with a minor.

On its own, the announcement that the pope had accepted Bishop Alexander Salazar’s resignation, made in the daily Bulletin issued by the Holy See Press Office, would have been unlikely to attract much attention. But a surprising follow-up open letter by Archbishop José H. Gomez of Los Angeles explained what had pushed Bishop Salazar to step down.

Archbishop Gomez, who took over in Los Angeles in 2011, acknowledged that the archdiocese had known of the accusation against Bishop Salazar since 2005, a year after he had been ordained a bishop, but had allowed him to keep working.

After learning of the reported misconduct, the archdiocese referred the allegation to the Vatican’s Congregation for the Doctrine of the Faith, which is tasked with looking into claims of sexual misconduct. The body “conducted an investigation and imposed certain precautionary measures on the ministry of Bishop Salazar,” the archbishop wrote in his letter, but he did not specify what these measures had been.