One of the men concerned has himself become infected with the virus, according to the state prosecutor in Darmstadt which is dealing with the case.
“We received a complaint from a man who had reason to believe that sexual contact with the woman had led to his becoming infected with HIV," a spokesman for the prosecutor told The Local. “He said he knew beforehand that he did not have the virus but was told about the young woman's status by a third party and had himself tested, and is positive.”
The 26-year-old mother of one is accused of having unprotected sex with three men between 2004 and 2006 without informing them of her HIV status.
The spokesman said efforts were being made to make contact with the two other men.
Benaissa was taken before an investigating judge after being arrested on Saturday night and is being held in investigative custody due to what the prosecutor describes as a danger that she might "reoffend."
Her lawyers are now expected to examine the files in the case and possibly challenge her custody.
If convicted of grievous bodily harm, she could face a prison term of between six months and ten years.
Benaissa, who has a past with addiction and theft, joined No Angels after the band was formed during a television talent casting show in 2000. The band has since sold some five million albums, but tanked at the Eurovision Song Contest in May 2008, taking 23rd place out of the 25 countries that participated.