LOS ANGELES — Federal prosecutors said Thursday that they had charged Ed Buck, a small-time Democratic donor and political activist, with a federal drug crime in the death of one of two men who died of overdoses in his West Hollywood home.

A criminal complaint also detailed a disturbing pattern in which the authorities said that Mr. Buck had exchanged drugs and money for sexual favors. There were at least 11 victims in the last two years, according to the complaint, including one who said he left Mr. Buck’s apartment after overdosing last week and called 911.

In the case of Gemmel Moore, who died at Mr. Buck’s apartment in July 2017, Mr. Buck, 65, was charged with distribution of methamphetamine resulting in death, which carries a mandatory minimum sentence of 20 years in prison, and a maximum sentence of life. He is being held in federal custody.

Of the 10 victims in addition to Mr. Moore, who was 26, nine said Mr. Buck had administered drugs to them or had strongly encouraged them to use drugs, Nicola T. Hanna, the United States attorney in Los Angeles, said at a news conference on Thursday.