The business cards handed to men at the corner of a grocery store didn't say much. Just a first name, a cellphone number and a color picture of a nude white female and the phrase free delivery. But their simplicity made clear the illicit purpose: sex. Authorities say the cards solicit customers for highly organized prostitution rings that cater to Hispanic immigrants and chauffeur women from out of state. Although prostitution crosses ethnic and racial lines, these immigration-related cases raise complex questions about the interplay of local and federal law and are likely to pose special challenges in the push against illegal immigration that began this week. The police department has said it will treat illegal immigrants who are criminals differently from those who are crime victims. But in prostitution cases, the women involved might be both. "A lot of girls we've interviewed don't even know what city they are in or what state they're in," said a police spokesman that has handled several of the prostitution cases. As the largest minority group in the U.S., Hispanics/Latinos are disproportionately affected by HIV/AIDS. Latinos in the U.S. represent 15.3% of the population but account for 21% of new HIV infections and New York State continues to lead the country with the largest number of Latinos living with AIDS.