Fewer than half of rapes committed in the U.S. are reported to the police, and the vast majority of reported rapes never lead to arrests. What are these cops thinking? For a study published this month in the Journal of Interpersonal Violence, Dr. Rachel Venema, a social work professor at Calvin College, interviewed 10 cops working in the police department of a midsized Midwestern city about their experiences responding to reports of sexual assault. Seven of the police officers were male, six of them were white, and their ranks ranged from patrol officer to detective to sergeant. It’s a very small sample, but it provides a fascinating peek into how one police department deals with rape reports in the face of limited departmental resources, and the officers’ own assumptions about who constitutes a “real” victim.

One officer told Venema that when a rape report is called in, they’ve “got to decide as a department how much resources we want to put into this.” In other words, that cop continues, “What’s the chances of this one being true, you know?” One officer told Venema that “definitely over a third, probably approaching … 40 or 45 percent” of sexual assault reports the officer fielded were either “outright recanted by the victim” or else raised “serious questions of the veracity” of the report. That’s probably an overstatement: The officers also told Venema that they were more likely to remember rape reports they deemed false than ones they believed checked out.

In further interviews with the officers, Venema found that cops often raised “serious questions” about rape reports that could very well be legitimate. If the alleged victim has a potential ulterior motive for claiming she was raped—like covering up for cheating, getting pregnant, or coming home late—she raised cops’ suspicions. Victims who failed to strike the correct emotional balance also risked not being believed. “Everybody’s gonna be different,” one officer said, and not “everybody’s gonna be distraught,” but if a woman reports a rape and is “very matter of fact about it,” she seems less credible. Incidents in which a victim has been drinking “are darn near impossible” to pursue, one said. In those cases, “You know the bad guy’s getting away with it.” And women who report to the police without obvious signs of injury—“their clothing is ripped or bite marks, scratches”—are out of luck. Without signs of physical violence, “you gotta think about the burden of proof we have which is beyond a reasonable doubt. It’s not gonna be there,” one officer said. Another was more blunt: “If there is no physical evidence and you said you got raped, did you get raped? … No.”

Cops’ beliefs about what constitutes a credible rape victim often prejudices their reporting of the incident and can affect whether the case moves forward. Often, if “there’s any inclination that there might be another motive,” the officers subject the alleged victim to “a light interrogation” to attempt to assess her credibility, a measure that one officer said is “very unique” to sex crimes. If the officers conclude that the victim may not be credible, the suspect may not be questioned at all. (Police mistreatment is one reason victims cite for withdrawing a report of rape or else not calling the cops in the first place.) One officer told Venema that cases had been “jeopardized” after a responding officer’s personal “judgments” showed up in the police report, which later showed up in court. And often, responding officers never learn how the cases pan out—so even if a report they’ve deemed fishy turns out to be credible, they never think to challenge their initial assumptions about the victim. “We don’t get any feedback from the detective as to what happened with the reports,” one officer said, so “if I don’t hear anything about it … I’m thinking it got shit canned.”

Some of the officers Venema interviewed acknowledged that the practical realities of sexual assault police work are frustrating and sad. And at least one officer said that cops with more experience investigating sex crimes know that the responding officer’s judgments are often “inaccurate” and that alleged victims are routinely “misjudged.” One bit of good news: Even when officers had suspicions about the veracity of a report, they had to still complete the necessary paperwork and hand it off to detectives. “I would love to just be able to can it off my desk today and not waste my time on it, but you can’t,” one said of ambiguous reports. “You got to make sure you cover everything.”

In theory, there’s a big difference between a rape report that’s simply not true and one that’s unlikely to lead to an arrest and conviction. But at least in this police department, the distinction can be lost on officers—from their perspective, they’re both a waste of time.