D.C. Mayor Muriel Bowser addresses the crowd at the More For Housing Now rally at the Foundry United Methodist Church in Washington, D.C. on March 18. (Jonathan Newton/The Washington Post)

D.C. Mayor Muriel E. Bowser (D) is set to announce on Thursday legislation that would enhance the rights of victims of sexual assaults, particularly juveniles, and expand what can be considered a crime during an attack.

Measures being proposed reflect year-long deliberations of an independent task force formed to address concerns that rape cases from several years ago had been mishandled and that younger victims lacked the same resources offered to adults.

The bill was submitted last week, and Bowser plans to discuss details during a Thursday news conference. It adds provisions to a sexual assault victim’s rights act passed in 2014. It would allow victims a greater choice of advocates to be present during interviews with police and prosecutors, and it would require prosecutors to tell victims why a case might not be taken to court.

In addition, the bill would allow children as young as 12 to be provided advocates to help them navigate police and court proceedings. Those services are currently offered only to adult victims. Victims may be distrustful of law enforcement or believe their cases are not being handled with the appropriate decorum or respect, and the trained advocates act as guides and counselors.

“I think this bill will contribute to more victims and survivors accessing help,” said Michelle Garcia, director of the D.C. Office of Victim Services and Justice Grants. “We know that when victims feel supported, they are more likely to engage with and stay engaged with the criminal justice system. . . . I think it will have a big impact in a number of ways.”

Issues regarding the handling of sexual assault cases emerged in 2013 when Human Rights Watch accused the D.C. police of fumbling investigations, losing reports and filing others away as unfounded without having conducted a thorough investigation. Police disputed the findings.

The task force also considered the case of Danielle Hicks-Best, who was 11 when she reported to D.C. police in 2008 that she had been raped by older youths. Hospital reports detailed her injuries and a witness was questioned, but in the end only she was arrested — on charges of lying to police.

Hicks-Best, who is now an adult, chose to identify herself publicly in hopes of helping other young rape victims. Her case helped drive the bill’s proposal to expand the use of youth advocates.

There have been 67 sexual assaults reported in the District so far this year, a 29 percent drop from the 94 reported in the same period last year.

The bill would also, for the first time, make it a crime for a person to remove clothes from a victim without consent. Garcia said that provision would make it easier for prosecutors to target cases that otherwise might not be pursued.

Garcia said such cases involve women who say they woke up after having been drinking or secretly drugged and have a “strong suspicion they have been assaulted and know who the perpetrator is.” Garcia said that the suspect often admits he “removed her clothes, but that’s all he did.”

Bridgette Stumpf, co-executive director of the Network for Victim Recovery of D.C., which provides the advocates who meet with sexual assault victims, said the bill addresses many issues that are needed to help in making arrests and prosecutions. She noted that sexual assault is one of the most underreported crimes.

In addition to expanding the work of the advocates, Stumpf said the bill also makes it easier for victims to obtain the results of rape kits — extensive tests done at hospitals to help prove a sexual assault — and allows victims to order law enforcement to preserve the kits up to the statute of limitations of the specific crime. That will help protect evidence should a suspect emerge years or, in some cases, decades later.

“Expanding the rights of advocates and survivors helps victims process their experiences, process their options and helps them decide how to move forward,” Stumpf said.