SACRAMENTO, Calif. – Prosecutors have taken the unusual step of detaining an alleged teenage rape victim who has a history of running away, saying she is a key witness against a man prosecutors say is a career criminal and serial rapist.

Victims’ rights advocates are joining the 17-year-old foster child’s attorneys in arguing that her detention, upheld three times by two superior court judges, could discourage other victims from reporting sexual assaults.

“This is a very rare step for us. It’s really the last thing we want to do, but we do feel that there is a public danger that has to be balanced here,” Sacramento County Assistant District Attorney Albert Locher said Monday.

The girl has been held in juvenile hall since March 23. Her attorneys are proposing that she be released to a foster or group home with a GPS ankle bracelet.

“She’s being treated like a criminal without having done any criminal act. In fact, she’s the victim,” said attorney Lisa Franco, who is challenging the decision to hold the girl as a material witness to ensure she appears at the trial of Frank William Rackley Sr., 37.

“This is just sending a chilling effect out there for people not wanting to report crimes and rapes. In the larger scope of things it’s going to give other people more chance to commit crimes because people will be afraid to report.”

The Associated Press is not naming the girl because of her age and because she is an alleged sexual assault victim.

Prosecutors had to dismiss charges once against Rackley when the girl failed to appear, though they were able to charge him again with the same crimes the next day, according to court documents.

The girl ran away twice from her foster home and did not show up for Rackley’s preliminary hearing in October or his first scheduled trial date in February, according to an affidavit by Deputy District Attorney Alan Van Stralen.