LaTisha Nixon, who reportedly names Buck and the Los Angeles County District Attorney as defendants in the lawsuit, said she grew frustrated after authorities failed to file criminal charges for the 2017 overdose death of her 26-year-old son Gemmel Moore.
Moore, a black male escort, was found by police on July 27, 2017, inside the 63-year-old's apartment. Moore's death was initially classified as an accidental methamphetamine overdose.
Buck, a well-known figure in LGBT political circles, has given more than $500,000 to a range of Democratic groups and candidates — including Hillary Clinton, Barack Obama and Los Angeles Mayor Eric Garcetti.
According to NBC4, the suit was filed in LA Superior Court and alleges wrongful death, sexual battery, hate violence, drug dealer liability, negligence, infliction of emotional distress, and two violations of civil rights. Nixon also accuses Buck of personally administering the drug that took her son's life.
Buck's attorney Seymour Amster said they did not yet see the lawsuit but vowed to “fight the allegations vigorously,” adding that there’s “more to the story than is being told.”
The District Attorney's Office reportedly declined to comment.
Moore's death was initially considered an accidental drug overdose. After an additional inquiry due to writings in Moore’s journal and pressure from his family, the Los Angeles County District Attorney’s Office concluded that the “admissible evidence is insufficient to prove beyond a reasonable doubt” that Buck gave Moore drugs or is responsible for his death.
Last month, a second black man, Timothy Dean, was found dead of an overdose in Buck’s home. Dean, 55, reportedly had a relationship with Buck years before Moore’s death.
Dean reportedly warned his friends to steer clear of Buck and referred to him as a "f---ing devil" and "a horrible, horrible man.”
Dean is said to have specifically told a friend in the fall that he had no intention of visiting Buck, and that “he didn’t want to end up dead.”
Hollie McKay and Christopher Carbone contributed to this report.