Rape is different from other crimes. Not only does it involve a violation more profound than any other crime but it also comes with a social stigma that forces victims to relive the pain again and again. No one suggests that a victim of a carjacking was really asking for it. No one asks whether an assault might really have been consensual. When a robbery victim is on the witness stand, the most private details of her life are not dissected under cross examination.

It is often too difficult for rape victims to come forward, to report their crimes and to see to it that their attackers are brought to justice. The problem is not that women routinely make up rape allegations — who would willingly submit themselves to such unjust public humiliation? Yet the statistics reported Sunday by The Sun's Justin Fenton show that Baltimore police who investigate sexual assaults routinely conclude that reports of rapes are unfounded. Four in 10 calls to 911 in which Baltimore residents say they have been raped result in no report at all, and in the cases when police do take a report, they conclude one third of the time that the allegations are unfounded. That means that if a woman in Baltimore calls to report a rape, better than half of the time, police will do nothing about it.

Worse, police reports obtained by The Sun and reviewed by Mr. Fenton show a disturbing pattern in which detectives aggressively question those who say they have been sexually assaulted, a process that, intentionally or not, gives victims the impression that the focus of the investigation is to prove that the victim is lying, not to catch and prosecute the attacker. Faced with those circumstances, and the certainty that persisting would only mean more pain, many women simply drop the matter.

The result is that Baltimore has a higher rate of unfounded complaints — by far — than nearly any other city in the nation. Baltimore is one of only a handful of cities in the nation with more homicides than rapes, and the number of rape cases here has, for reasons no one can explain, dropped nearly 80 percent since 1992, a period in which rape cases declined by 8 percent nationally. Meanwhile, the proportion of rape reports deemed unfounded has increased fivefold since the late 1990s.

Does this indicate a sudden epidemic of Baltimore women lying about being raped? The top commanders in the police department wouldn't talk to Mr. Fenton before his report ran in the newspaper, so we don't know what their explanation is for Baltimore's exceptional rape statistics. However, a former commander of the unit that investigates sex offenses told Mr. Fenton that many reports of rape are made by women for "ill gain" — such as to explain to a husband or boyfriend why they hadn't come home that night. That presumption is as offensive as it is nonsensical.

If police were initially unwilling to confront the disturbing pattern Mr. Fenton revealed, Mayor Stephanie Rawlings-Blake, to her credit, took immediate action after being shown the statistics. She ordered an audit of the department's procedures. In a statement on Sunday, she got it right: "Sadly, rape is one of the most underreported crimes because women are often ashamed and afraid to confront their attackers. We need to do everything in our power to ensure victims of sexual assault feel safe reporting incidents to police. No victim should suffer in silence." City Council President Bernard C. "Jack" Young on Sunday echoed that sentiment, saying the city must ensure that victims have confidence that when they report something "it's not going to get thrown out."

Commissioner Bealefeld said at an unrelated news event Sunday that the report "draws attention to a situation we've been focused on." Evidently the department hasn't been quite focused enough. The audits of department procedures in rape cases need to be swift, and their results need to be very transparent. The department has a lot of explaining to do, and it needs to take significant, public and sustained action, as has been done in Philadelphia and other cities, to convince residents that when they suffer the most extreme violation, they won't be victimized again by a callous, cynical police department.