How False Reporting Beliefs Change Investigator Behavior (Even When They Don’t Realize It)

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Ask a room of law enforcement professionals what percentage of sexual assault reports are false, and the answers will span an enormous range. Some will say a few percent. Others will say half. A few will say most.

That number matters more than it appears to because the figure a professional carries in their head rarely stays in their head. It shows up in how they open an interview, what evidence they pursue, how they write a report, and how a case ends, which is usually without any conscious decision to stop working on it.

The Number in the Room

For decades, one study did outsized damage to this field. Kanin’s 1994 research reported a 41% false reporting rate, and that figure still circulates in briefing rooms and training sessions.

The problem is how it was produced. The determination that a report was false rested entirely on the conclusions of detectives in a single small police agency, with no independent verification and no systematic evaluation of how those conclusions were reached. As David Lisak has observed, this violates a cardinal rule of science: the study used the very judgment under examination as its measuring instrument.

When researchers apply rigorous methods and consistent definitions, the findings converge in a narrow band of roughly 2% to 8%:

• Lisak et al. (2010): 5.9% of 136 reports made to a northeastern university over ten years
• Spohn, White, & Tellis (2014): 4.5% of Los Angeles Police Department cases from 2008
• EVAWI’s Making a Difference (MAD) Project: 7% of 2,059 cases across eight US communities
• Kelly, Lovett, & Regan (2005): 9% of 2,643 British cases on initial classification, dropping to 3% when strict evidentiary criteria were applied

EVAWI’s position is that no one can know the precise figure because a report can only be established as false through the evidence of a thorough investigation — never through a preliminary impression. But the range is not seriously disputed among researchers.

The gap between the actual prevalence of 2–8% and 41%, which many professionals still assume is correct, is large. It’s also where real and lasting damage can be done to survivors who report their experience to law enforcement.

Belief Shows Up in the First Five Minutes

Skepticism is rarely announced. It leaks.

It surfaces in tone, in posture, in which parts of an account get a curious follow-up question and which get a flat pause. Victims read it accurately, and they read it fast.

What follows is the pattern EVAWI describes as the cycle of suspicion. An investigator who doubts a report communicates that doubt, however unintentionally. The victim, sensing it, disengages: they stop returning calls, decline a follow-up interview, or ask to drop the case. The investigator then reads that withdrawal as confirmation: if this were real, they would have cooperated.

It is a closed loop. The belief produces the behavior that appears to justify the belief. And at no point in the loop does anyone gather evidence about whether the assault actually occurred.

The Mirror Image: The Cycle of Sympathy

Less discussed (and just as consequential) is what happens when a suspect presents well.

Suspects in non-stranger sexual assault cases are frequently calm, cooperative, articulate, and likeable, and sometimes noticeably more composed than the victim, whose demeanor may be flat, fragmented, or visibly distressed. When an investigator finds the suspect credible on that basis, the suspect’s account begins receiving the benefit of the doubt while the victim’s receives the scrutiny.

EVAWI describes the result plainly: The victim starts to feel like a suspect, and the suspect starts to feel like a victim.

It Changes What You Look For

Confirmation bias is not a character flaw; it is how human attention works. Once a hypothesis is in place, we notice what fits it and skim past what doesn’t.

In practice, that looks like:

Corroboration asked of one party only: Inconsistencies in the victim’s account get chased down. Inconsistencies in the suspect’s account get explained away.

Offender-focused work never started: Prior police contacts, past dating and intimate partners, patterns of prior behavior, database and open-source searches — the work that reveals who a suspect actually is and what he may have done before — goes unexplored, because the case has already been mentally filed.

Absence of evidence read as evidence of absence: Sex assault can happen with no visible injury, a negative toxicology screen and no DNA evidence. Each has ordinary explanations. Drugs commonly used to facilitate sexual assault metabolize quickly and are often undetectable by the time a sample is collected. Most sexual assaults produce no visible genital injury. None of these findings indicates that an assault did not occur.

It Changes What You Write

Report language is where a private belief becomes part of the permanent record, and it is one of the easiest places to correct.

Writing that a victim alleges the suspect did something subtly signals doubt. Writing that the victim reports it is simply more accurate: they made a report, and that is a fact regardless of what the investigation later establishes.

Similarly, describing events in the language of consensual sex when the report is of non-consensual sex misstates the case. “The victim performed oral sex on the suspect” and “the suspect forced his penis into the victim’s mouth” describe very different events. Supervisors, prosecutors, defense attorneys, and eventually jurors all read that report. It should describe body parts and acts committed, not carry an implication about consent. (EVAWI’s training on Effective Report Writing: Using the Language of Non-Consensual Sex covers this in depth.)

It Changes How Cases End

The most consequential effect appears at the point of case clearance.

Because a “false” or “unfounded” designation is so often made on the basis of investigator opinion rather than evidence, variation between agencies is extraordinary. As the research literature puts it: some police agencies cannot find a single rape complaint with merit, while others cannot find a single rape complaint without merit. The difference is not the crime. It is the culture.

Two practices deserve particular scrutiny.

Polygraph and voice stress analysis used or threatened as a screening tool for victims. These instruments respond to physiological stress, which traumatized people have in abundance. They do not detect lying. Their practical effect is to pressure victims into withdrawing, which establishes nothing about whether a report was false.

Under the Violence Against Women Act, jurisdictions receiving certain federal grant funds are restricted from requiring or requesting that a victim submit to a polygraph as a condition of proceeding with an investigation.

Written release waivers presented during an initial interview, allowing an agency to close a case at the victim’s request before any meaningful investigation has occurred. As EVAWI has noted, this sidesteps a law enforcement agency’s responsibility to investigate a reported felony.

What Actually Helps

None of this asks an investigator to believe every report is true. It asks for recognition that credibility assessment is the outcome of an investigation, not the entry point to one.

Concretely:

• Begin with an orientation of belief and support, then follow the evidence wherever it goes.
• Treat trauma responses (fragmented memory, non-linear accounts, delayed disclosure, flat affect) as expected, not as credibility indicators.
• Hold victim and suspect accounts to the same evidentiary standard.
• Complete the offender-focused work before forming a conclusion.
• Audit your agency’s unfounded and exceptionally cleared rates. If they sit far outside comparable agencies, the explanation is probably in your processes, not your caseload.

Supervisors matter most here. An individual investigator’s beliefs shape their own cases. A supervisor’s beliefs shape every case that crosses their desk.

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