Donny Ray Williams Jr. leaves D.C. Superior Court on Friday. (Susan Biddle/FOR THE WASHINGTON POST)

A former senior congressional aide was indicted this week in D.C. Superior Court on charges that he sexually assaulted two women after drugging them with a sedative that he allegedly put in their drinks.

Donny Ray Williams Jr., 36, who served as staff director for a Senate subcommittee and worked in the offices of several members of Congress, gave at least one woman Ambien and assaulted her while she was unconscious, according to court papers.

Williams was charged with 10 counts of first- and second-degree sexual abuse and related charges in connection with attacks that authorities said occurred between July and December 2010. During that time, according to his profile on the LinkedIn Web site, Williams was staff director of a Senate Homeland Security and Governmental Affairs subcommittee.

A third woman made similar allegations against Williams, attorneys and Williams said, and a fourth woman said that he threatened her. As a result of that fourth allegation, Williams was indicted on one count of threatening to injure or kidnap a person. Additional details of that charge were not made public.

Outside the courthouse Friday, Williams said the allegations are “absolutely and completely false.”

“I’m not guilty. I’ve never done anything to hurt anybody. I tried to live my life to help people,” he said, his voice cracking with emotion.

In response to a question about his Capitol Hill career, Williams said that “everything was destroyed.”

“Until this is over,” he said, “I don’t have a future.”

According to his LinkedIn profile, Williams was a member of the staff of the Senate Homeland Security and Government Affairs disaster recovery subcommittee from 2002 to 2007 and staff director for the same committee’s state, local and private sector preparedness and integration subcommittee from April 2010 to July 2011.

The profile says he is now managing director of a private company.

According to his profile, he began his Capitol Hill career in 1999. He worked for panels chaired by Sen. Joseph I. Lieberman (I-Conn.) and Sen. Mary Landrieu (D-La.). He also said he worked for Sen. Herb Kohl (D-Wis.), Rep. Elijah E. Cummings (D-Md.) and Rep. Jan Schakowsky (D-Ill.). The Washington Post confirmed that he had held those positions.

Williams was arrested last year in connection with one alleged assault and made his first appearance before a judge May 13, 2011, according to court records.

Williams was released from jail, but at a subsequent hearing he was ordered to stay away from the alleged victim.

In that incident, the woman visited Williams’s Northeast Washington apartment July 22, 2010, to discuss issues before the Senate subcommittee, including Hurricane Katrina and the oil spill in the Gulf of Mexico, according to an arrest warrant filed in court.

While she was at the apartment, Williams allegedly prepared her a sparkling water and vodka. The woman said she drank it and lost consciousness.

When she came to, according to the warrant, her pants had been removed and she felt a “burning sensation” in her vaginal area. She also was groggy. Williams drove the woman home, the court papers say. She later went to George Washington University Hospital, where she was examined.

On July 27, detectives went to Williams’s apartment, and he told them that he had prescription medication he was taking for back pain, Ambien for a sleep disorder and Adderall for attention-deficit hyperactivity disorder, according to court papers.

At the hearing Friday, Assistant U.S. Attorney Sharon Marcus-Kern said she expected the trial, which is set to begin March 19, to last about two weeks.

Williams has admitted having sex with at least one of the alleged victims, Marcus-Kern said at the hearing. She did not elaborate.

Williams has been ordered to undergo drug testing, according to court records.

According to his biographical information on LinkedIn, Williams left Capitol Hill two months after his arrest.

Williams’s attorney, Jason M. Kalafat, said his client “denied” the allegations and would “probably” go to trial.

Alice Crites contributed to this report.