Strategic Use of Evidence: How and When to Reveal What You Know
Strategic Use of Evidence (SUE), developed by Pär Anders Granhag, Maria Hartwig, and colleagues, is a research-supported suspect-interviewing technique that asks a deceptively simple question: when should you tell the subject what you already have? The research answer, later and in a planned sequence, improved deception-detection accuracy in controlled studies, and the same planning leaves a clearer record of what the person said before the evidence was disclosed.
A credited tool in the Test direction; it governs the evidence plan.
A research program at the University of Gothenburg
Strategic Use of Evidence emerged from a sustained line of research led by Pär Anders Granhag, Maria Hartwig, and colleagues, beginning in the early 2000s. The research program was a direct response to a long-standing problem in the field: lay people, and most professionals, perform only slightly better than chance at detecting deception from behavioral cues alone.
Granhag and Hartwig reframed the problem. Instead of asking what cues distinguish liars from truth-tellers, they asked what behavior interviewers could elicit that would distinguish them. The answer that emerged from their research, most of it controlled laboratory studies with mock suspects, was a structural change in how evidence is used during the interview itself.
SUE is now one of the most extensively researched suspect-interviewing techniques.
Delayed disclosure tests the account, not the person
SUE rests on a research finding about strategies. In the research, guilty mock suspects tended to use strategies to manage information they thought could incriminate them, while innocent ones mostly reported telling the truth as it happened (Hartwig, Granhag & Strömwall, 2007). A guilty subject who knows what evidence the investigator has can shape an account to fit it. One who does not know must guess, and in the research, liars questioned before the evidence was disclosed contradicted it more often than truth-tellers did. Truth-tellers can still be inconsistent with the evidence, through faulty memory, a misunderstanding, or a flawed record, which is why a difference is something to explore, never proof.
The diagnostic value of the interview, in other words, comes from the gap between what the subject says and what the investigator already knows. To preserve that gap long enough to use it, the investigator has to resist the urge to confront, to lay the cards on the table early. The technique is named for that discipline: the strategic use of evidence is, above all, the patient use of evidence.
SUE is not a "gotcha" technique. It is a structured way to give a subject the room to commit to an account before they know what they have to align with, and to compare what they say against what the case file already shows.
A planned five-stage structure
SUE is conducted as a structured interview, not a spontaneous trick. The sequence below is how ASC teaches SUE-informed interviews. It reflects SUE’s core principles (evidence assessment, strategic questioning before disclosure, and late or incremental disclosure) but is ASC’s teaching structure, not a formal SUE protocol. Each stage has a specific purpose and is documented as part of the case record.
The investigator inventories every piece of evidence: physical, digital, witness, surveillance. Each item is rated for source reliability, specificity, and risk of disclosure. The interview plan is built around which items will be held back and which can safely be referenced early.
A genuine rapport phase, followed by an open invitation for the subject to tell the story in their own words, uninterrupted. The interviewer listens for the shape of the account: what is included, what is omitted, what is volunteered.
Targeted, open follow-up questions explore the regions of the account where the investigator has evidence, without revealing what that evidence is. The goal is to lock the subject into specifics: times, locations, sequences, presence of others. The interviewer is not arguing; they are listening.
Evidence is introduced in a deliberate sequence, typically least-to-most incriminating, or in an order that lets each new item test a specific portion of the account. After each disclosure, the subject is given an opportunity to explain. The investigator documents both the evidence shown and the response given.
A clean close: the subject is given a final chance to add or amend, the interview is summarized, and the record reflects exactly which evidence was disclosed and at which point. That paper trail is the primary downstream value of SUE, it gives prosecutors and triers of fact a clean record of what the subject said before they knew the case.
What the studies compared
The core SUE studies compared timing and training, not SUE against accusatorial interrogation. In Hartwig, Granhag, Strömwall, and Vrij (2005), observers judging mock-suspect interviews were more accurate when the evidence had been disclosed late (61.7%) than early (42.9%). In Hartwig, Granhag, Strömwall, and Kronkvist (2006), police trainees taught to use the evidence strategically reached 85.4% accuracy against 56.1% for untrained trainees, because the liars they questioned became more inconsistent with the evidence. These are controlled studies with mock suspects, and the mechanism is not that the interviewer becomes a better lie-detector; it is that the structure of the interview produces a more diagnostic record. Statement-evidence inconsistencies are objective and reviewable; “gut feel” cues are not.
ASC also values a practical consequence of the structure. Because the account comes first and the evidence is introduced in a planned way, an innocent person has room to give their account in full before anything is put to them, and the record shows that they did.
The record reflects what was said, when, and against what evidence. That is the kind of record built to withstand legal review.
What investigators must plan around
SUE is not a substitute for due process. Miranda warnings, custody status, voluntariness, attorney presence, and recording requirements all apply on their normal terms. The technique works inside those constraints, not around them. In a custodial interview, planned disclosure is sequenced after rights have been waived; in a non-custodial interview, the same sequencing applies with no rights threshold to clear.
SUE also requires careful handling of confidential sources, ongoing investigations, and discovery obligations. Withholding a piece of evidence during interview is a tactical choice; it does not change the prosecution's downstream duty to disclose. Investigators have to know, in advance, which items can be referenced openly, which can be alluded to without compromising sources, and which cannot be raised at all without coordination with the prosecutor.
Done properly, SUE produces an interview record built to hold up under scrutiny, because every disclosure is planned, documented, and tied to the evidentiary inventory built before the interview began.
A credited tool in the Test direction
ASC runs SUE on the Teach To Talk® standard. The interviewer settles the person’s exact position before any comparison, raises one discrepancy at a time, introduces evidence through the Disclosure Ladder, returns to any earlier answer that proved misleading, and, when the interview can properly continue, attempts direct presentation of the remaining material evidence before closing. ASC never bluffs, exaggerates evidence, or reads behavior as a verdict.
Inside the Adaptive Strategies Compass™, SUE is a credited tool in the Test direction, which answers one question: does the account hold up against the evidence? The interviewer turns there only after the account has been given, developed, and clarified, and a material piece of evidence appears to conflict with it. SUE governs the evidence plan. ASC’s Difference Audit and Fair Challenge Test, the ASC tools of the same direction, decide whether a difference is ready to put to the person (see Fair Challenge).
The Disclosure Ladder
The Disclosure Ladder is Joe’s practitioner teaching formulation of three ways to introduce evidence: future tense, soft confirmation, and direct presentation. The account-first, delayed, and incremental disclosure principles underneath it come from SUE and are not claimed as original. It is not the Evidence Framing Matrix and not a formally validated SUE protocol. Source-neutral questions come first: during account development, the interviewer asks how a credential is ordinarily kept, whether it was working, or whether anyone else had access to it, without naming an evidentiary source. The order in which the three are taught is not an instruction to use all three back to back.
“If I were to review the access logs, would there be any reason your card would be on that list?” A conditional question, asked once the account is settled, about evidence the investigator actually holds or can lawfully obtain. The interviewer may already have reviewed the logs and is keeping that in reserve.
“I have reason to believe that your access card was used on that day. What can you tell me about that?” An accurate acknowledgment of a real basis for the concern, without revealing the source or the details. It is never a bluff. The interviewer develops the response before deciding whether to disclose more.
“I have reviewed the access logs, and I know your card was used.” Used only after reviewing the record and confirming it supports that conclusion, with its limits stated: knowing the card was used is not the same as knowing who used it.
If the person gives an explanation, the interviewer explores it before disclosing more. Direct presentation is the final introduction taught, not a finish line to race toward, and soft confirmation is not an automatic stopping point. See the full Ladder and a worked example on the Fair Challenge page.
Test the material, not the person.
SUE inside From Information to Evidence and The Academy
ASC teaches SUE as a core component of two flagship law-enforcement programs: From Information to Evidence, which focuses on how investigators move case material through the interview to produce defensible records built to withstand legal review, and The Academy, ASC's most advanced practitioner course.
Instruction covers the underlying research, the five-stage sequence, evidence-inventory worksheets, and extensive supervised role-play with feedback. Students practice both ends of the table, running the interview and being interviewed, so they can feel the structural difference between a confrontational interview and a SUE-structured interview from inside the chair. Integration with the rest of the Teach To Talk method is explicit: the Teach To Talk standard opens the conversation, the Adaptive Strategies Compass guides real-time choices, and SUE structures the disclosure of what the case file already shows.
The discipline ASC asks of its graduates is the discipline the research demands: do not show your hand until you have given the subject the room to commit to an account. The interview that follows tells you what you need to know.
Train your investigators in research-supported suspect interviewing
SUE is taught in From Information to Evidence and refined in The Academy.