How to Investigate Evidence for Exonerating Wrongful Convictions? The Wrongful Conviction Exoneration Handbook: Investigating Evidence
Last edited: 2026-08-26
Being unable to make others believe one's defense is a shared tragedy for the wrongfully accused. Compared to criminals behind bars, trusting court judgments is the normal choice for ordinary people. To exonerate a wrongful conviction, one must let the evidence speak; only with the truth that "facts speak louder than words" can one gain public trust. This article introduces specific methods for investigating evidence, because making evidence speak requires acquiring it first.
Method 1: Obtain the Complete Litigation Case File
When attending a court hearing, one can see a stack of documents at the judge's side; this stack of documents is the litigation case file. According to Article 54 of the Code of Criminal Procedure: "Documents pertaining to litigation that are required to be preserved by the court shall be compiled into case files by the clerk." In judicial practice, all processes of a judge handling a case are made into written records—for example, making a record of phone calls, retaining signed draft official documents, issuing case-progress scheduling slips, etc. All these records are collected in the case file. Through the case file, one can know what evidence the court investigated, which witnesses were summoned, and the investigation results. Therefore, the first step in investigating evidence is to obtain the complete litigation case file.
Obtaining the complete litigation case file means copying all the files in the judge's possession from cover to cover, page by page and serial number by serial number without omission, and scanning or digitally photographing color photos. In short, whatever the judge has in hand must be obtained in an identical manner. The method for obtaining the case file is applying for file review. The Code of Criminal Procedure stipulates that file review must be entrusted to a proxy attorney; defendants or accusers are not permitted to review files. During the ongoing litigation, an application may be made to the presiding judge. After the litigation is finalized, one must apply through extraordinary appeal, retrial, delivery-to-trial, or obtain consent from other civil, criminal, or administrative litigation judges to request the file transfer before applying for file review. The relevant laws and regulations are as follows:
Relevant Laws and Regulations on Applying for File Review in Finalized Cases
| Laws, Regulations, and Official Rulings | Key Provisions |
| Directions for Attorney File Review in Prosecutorial Agencies | 2. An attorney who has been retained to apply for delivery to trial, retrial, or extraordinary appeal may apply to the prosecutorial agency holding the case file to review the criminal case with a finalized disposition of dismissal or finalized judgment, as well as related cases with finalized dispositions of non-prosecution or suspension of prosecution. |
| Directions for Attorney File Review in Criminal, Administrative Litigation, and Juvenile Protection Cases at All Levels of Courts | 19. When reviewing files, an attorney may, in addition to viewing them, request the court to photocopy, transcribe, or photograph them on their own or by paying a fee, and may apply for the delivery of court electronic transcript discs or make copies of the recording and videotapes of the interrogation process attached to the criminal case files. |
| Research on Criminal Legal Issues, Volume 12, Issue 60, Discussion Agency: Taiwan High Court Taichung Branch Court | Legal Issue: Can an attorney retained by the defendant review the files before the court rules to commence a retrial? Discussion Opinions: View A: It is appropriate to permit file review. |
| Fa-Jian-Zi No. 1000806602, Discussion Agency: Supreme Prosecutors Office | Legal Issue: May defense counsel apply to review and copy case files and evidence for a finalized judgment case, and are they permitted to copy audio (video) tapes or discs? Ministry of Justice Research Opinion: It is not permitted to copy audio (video) recordings or discs within the file. |
Method 2: Investigate Attached or Externally Stored Evidence, Photographs, Videos, and Audio Recordings
The second step in investigating evidence is to inspect and tally all items of evidence recorded in the case file. Important documents recording evidence are listed below. The most crucial items that must be inspected are the evidence placed in evidence bags and the evidence stored externally in the stolen goods and evidence warehouse. After obtaining the evidence, for items that can be duplicated, such as photographs, videos, and audio recordings, duplication should be applied for; for items that cannot be duplicated, such as murder weapons, bloody clothes, or stolen money, photographs, measurements (size, weight), or other recording methods should be conducted.
Important Documents Recording Evidence Within the Case File
| Document Name | Description |
| (Police) Criminal Case Report | A criminal case report is a document transferring a case from the police station to the prosecutors office, which will specify the detailed inventory of transferred evidence in the evidence column. |
| (調查局) Case Analysis Report | A case analysis report is a document given to the prosecutors office by the Investigation Bureau when transferring a case, and it will specify the detailed inventory of transferred evidence in the evidence content column. |
| Search and Seizure Record and Seized Property Inventory (Voucher) or Catalog | For cases where search and seizure are conducted, there will be a seized evidence inventory (voucher) or catalog. |
| Post-Mortem Examination Case File | There will be detailed evidence collection records during post-mortem examinations of deaths. |
| Official Documents and Appraisal (Examination) Reports for Commissioned Appraisals and Reply Results | When the court commissions an appraisal, it will specify the transferred evidence in the official document, and the same applies when the appraisal agency replies. The appraisal (examination) report will also list the details of the appraised evidence in full. |
| (Prosecutors Office) Written Indictment | There will be records of evidence within the written indictment, and an evidence inventory will also be attached. |
| Official Document of the Prosecutors Office Transmitting Case Files to the District Court | After indictment by the prosecutors office, the case files and evidence will be handed over to the district court, and the official document will specify the names and quantities of transferred items, accompanied by a stolen goods and evidence inventory. |
| (Court) Evidence Bag, Stolen Goods and Evidence Inventory, Stolen Goods and Evidence Duplicate Sheet | There are dedicated evidence bags placed inside the court case file, and evidence stored externally in the stolen goods and evidence warehouse is registered in the stolen goods and evidence inventory (duplicate sheet). |
| (Court) Case File (Evidence) Index | When a case is appealed or remanded by the Supreme Court, a case file (evidence) index is prepared for the transfer of case files and evidence, which contains records of the evidence. |
| (Court) Written Judgment | There will be records of evidence within the written judgment, sometimes listing evidence in attached tables. |
Investigating the evidence recorded in the case file is the most crucial basic skill for exonerating wrongful convictions, with three objectives: First, to confirm the actual existence of such evidence; second, to examine the authenticity of written records; and third, to use new technology to process old evidence and discover the truth of the facts. Achieving even one of the above three objectives is sufficient to exonerate a wrongful conviction. The following summarizes the experience of the Ch'en Chien-t'ang (Note: Su Chien-ho) case to illustrate that key exonerating evidence was all in the original case file; it was only because the judges of the original trial were perfunctory and negligent that a wrongful conviction occurred.
Key Exonerating Evidence in the Su Chien-ho Case
| Key Evidence | Description |
| NT$24 in coins (Confirming the non-existence of evidence) | The retrial judge discovered that days after the NT$24 in coins were seized, the police had already returned them to the family. The NT$24 in coins seized by the first-instance judge were items subsequently planted by the police. |
| Prosecutor's Interrogation Audio Tape (Confirming unlawful interrogation) | The retrial judge examined the prosecutor's audio tape and found that the prosecutor's attitude was atrocious, and the transcript severely mismatched the interrogation content. |
| On-site Evidence Collection Video (New technology discovers the truth) | The judge of the second retrial remanding court commissioned Dr. Henry Lee (Li Ch'ang-yü) to use the latest computer technology to enhance the image quality of the on-site evidence collection video and conduct on-site reconstruction and appraisal of blood spatter patterns. |
Method 3: Investigate Case-Handling Information Omitted or Concealed by Investigative Agencies
The first two methods target evidence within the file; next, we will introduce how to investigate evidence outside of the litigation case file. First, one must investigate whether there is any case-handling information omitted or concealed by investigative agencies (such as prosecutors offices, police departments, the Investigation Bureau, the Agency Against Corruption, and the Coast Guard Administration). Article 2 of the Code of Criminal Procedure stipulates: "Public officials exercising criminal procedure programs shall pay equal attention to circumstances both favorable and unfavorable to the defendant regarding the case in question." According to the law, investigative agencies should submit whatever evidence they discover to the court for review. However, the realistic performance evaluation system, where clearance rates and conviction rates determine the rewards and promotions of investigative personnel, leads investigative personnel to pay attention only to evidence unfavorable to the defendant and often intentionally or unintentionally omit or conceal evidence favorable to the defendant. Conversely, if it is discovered that investigative agencies have omitted or concealed case-handling information, it may be evidence favorable to the defendant or even sufficient to exonerate a wrongful conviction. Commonly omitted or concealed case-handling information is summarized in the table below:
Commonly Omitted or Concealed Case-Handling Information
| Case-Handling Information | Description |
| Wiretap Reports, Audio Files, and Transcripts | Wiretapping units generally only submit excerpted transcripts, which often leads to the problem of taking things out of context. It is recommended to investigate the complete audio files or transcripts. |
| On-site Surveillance Camera Videos | The police often only submit excerpted surveillance camera video footage; it is recommended to investigate the complete audio files or transcripts. (Note: original text inconsistency preserved conceptually) |
| Crime Scene Investigation Reports, Evidence Collection Videos, and Photographs | The police often do not submit crime scene investigation reports and evidence collection videos, submitting only partial photographs; it is recommended to investigate the complete information. |
| Police Department Investigation Reports and Inquiry Records | The police often use the excuse of being unrelated to the case facts not to submit investigation reports and inquiry records prior to solving the case; it is recommended to investigate the police's prior case-handling information. |
| Full-process Audio (Video) Tapes and Transcripts of Police (Investigative) Interrogations | Police and investigative agencies often conduct multiple or prolonged interrogations but only submit audio (video) tapes and transcripts of partial processes; it is recommended to investigate the complete information. |
| Appraisal (Examination) Reports | Police and investigative agencies will submit evidence for testing on their own, but if the tests yield no results, or if the results are unrelated to the defendant, they often do not submit them. If it is found that items were sent for appraisal but no report is seen, it is recommended to investigate the results. |
The difficulty lies in how to know of its existence since the case-handling information has already been omitted and concealed, and how to unearth this evidence. This tests the case rescue workers' ability to organize and analyze cases. The five methods of organizing cases introduced in "Combat Manual" Issue 94 of this publication are all very important references. The table below uses the actual experience of the Cheng Hsing-tse (Cheng Hsing-tsê) case as an example to introduce methods for investigating evidence.
Methods for Investigating Police-Concealed Information in the Cheng Hsing-tse Case
| Police-Concealed Information | Investigation Method |
| The missing document for sending items for appraisal (Comparing document serial numbers) |
The official document from the Fengyuan Precinct sending evidence for appraisal started with the serial number "Feng-Ching-Hsing-Zi No. 001," followed sequentially by dash-one, dash-two, dash-three, dash-four, and dash-six; serial number "dash-five" was missing. The items sent for appraisal in "dash-four" and "dash-six" were both bullets from the scene; it is deduced that the missing "dash-five" document for sending items for appraisal might be the missing key bullet. |
| The missing on-site evidence collection video (Photographs proving recording took place) |
Photographs in the Taichung District Prosecutors Office investigation file show that on the day of the incident, police officers held video cameras at the scene to collect evidence, proving that the police filmed an on-site evidence collection video but did not submit it to judicial agencies. |
| The missing segment of the crime scene investigation video (Checking the hour, minute, and second of the video) | The crime scene investigation video displayed the hours, minutes, and seconds of the recording. However, after Cheng Hsing-tse told the prosecutor that he did not fire a gun, the recording time jumped directly from 02:20:23 pm to 02:23:28 pm; three minutes of video were cut out, proving that the video submitted by the police was not the original file. |
Method 4: Obtain Experimental Data and Fundamental Materials of Appraisals
Scientific case-handling is an important method for reducing wrongful convictions, but improper scientific case-handling has also caused many wrongful convictions. Because science does not make mistakes, but the "people" engaged in science do make mistakes. Appraisal institutions in Taiwan are almost all subordinate to investigative agencies, lacking independence in personnel and budget, which causes forensic personnel to tend to cater to the expectations of investigative agencies when selecting test items and interpreting experimental results, thereby producing conclusions unfavorable to suspects. Judges and prosecutors, also lacking scientific training, often accept appraisal conclusions wholesale and neither can nor wish to verify whether the appraisals are correct. This attitude of blindly believing in appraisal conclusions has caused many innocent people to suffer harm.
In practice, litigation case files often contain only appraisal reports (letters) recording conclusions, lacking the experimental data of the appraisal process and the fundamental materials used to form the conclusions, making it difficult to verify their correctness and error rates. Take DNA appraisal as an example: generally, only the appraisal result table is attached, but if one needs to determine the number of mixed DNA contributors (how many perpetrators there were), one needs to obtain the STR electropherogram and examine the STR genotype signal intensity ratio combination to determine the number of contributors. Therefore, if the cause of a wrongful conviction is an erroneous appraisal, investigating the experimental data and fundamental materials of the appraisal is the most crucial key.
Obtaining the experimental data and fundamental materials of an appraisal after a case is finalized is extremely difficult. In addition to asking judicial agencies to obtain them through retrial or extraordinary appeal procedures, one may also attempt to ask the Control Yuan to investigate and obtain them, or apply directly to the appraisal agency for acquisition pursuant to the Archives Act or the Freedom of Government Information Act.
Judge Requests Case Files, Overturning Investigation Bureau Appraisal
Forty years ago, Liu Hsin-shan, known as the "Circuit Breaker King," was accused of forging shareholders' meeting minutes and equity transfer documents. The Investigation Bureau appraised the text on the documents as having "scratched fluff." The first-instance judge did not personally inspect these two documents, but directly sentenced Liu Hsin-shan to 45 days in prison based on the Investigation Bureau's report, which also led to his company being liquidated and sold. Until 2012, while hearing a civil lawsuit requesting the cancellation of company ownership registration, a Taiwan High Court judge retrieved the two documents, which had been sealed for years, from the court's stolen goods and evidence warehouse, and compared the multiple appraisal reports successively issued by the Investigation Bureau, confirming that there were no alterations at the key points and that the records all bore shareholders' signatures. The text of "scratched fluff" adopted by the original judgment did not actually affect the authenticity of the documents. Forty years later, the judge finally cleared Liu Hsin-shan's name. The key to exonerating this case lay in finding the fundamental materials of the appraisal—namely, the two documents of the shareholders' meeting minutes and the equity transfer documents—to examine the truth or falsity of the appraisal conclusion. (Refer to Taiwan High Court 98-Chung-Su-749 Civil Judgment)
Method 5: Re-interview Witnesses
Witness testimony frequently suffers from confusion, errors, lying, shirking responsibility, and even frame-ups. If a judge fails to investigate and adopts unreliable testimony, a wrongful conviction will result. After a judgment is finalized, the practical method to overturn witness testimony is to file a complaint for the crime of perjury. However, unless there is strong contradictory evidence or the cooperation of the witness themselves, most such complaints end in failure.
The method of last resort in investigating evidence is re-interviewing witnesses, because winning the cooperation of witnesses and making them willing to speak the truth is extremely difficult. Once handled improperly, one may instead be perceived as harassing witnesses or even violate the law as a result. It is recommended that wrongfully accused persons or their families do not independently re-interview witnesses, but seek assistance from government agencies, public-interest organizations, or impartial third parties. Currently, the most effective unit for re-interviewing wrongful conviction witnesses is the Control Yuan; it is recommended to prioritize seeking the concern and assistance of Control Members to have the Control Yuan dispatch investigators to re-interview witnesses and uncover the truth of the case.
A Night Without a Moon
Regarding the 2002 Houfeng Bridge woman falling-to-death case, on August 15, 2012, the Control Yuan published an investigation report demanding the Ministry of Justice to file a retrial and extraordinary appeal. The Control Yuan report pointed out that the finalized judgment considered the moonlight brightness and visibility on the night of the incident to be quite clear, and that the relevant location where witness Wang was situated could indeed clearly see the situation on the bridge at the time of the incident, thus adopting his testimony to sentence the defendant guilty. However, upon re-interviewing witness Wang and retrieving meteorological data from the Central Weather Administration dated December 6, 2002, the Control Yuan discovered that the night of the incident was the third day of the lunar month, the moon set at 7:15 pm, and at the time of the incident around 1:00 am, there was absolutely no moon appearing, and the night was overcast with poor visibility. Witness Wang's testimony had obvious flaws, and the evidence collection of the finalized judgment clearly contained errors; a retrial should be filed to ascertain the truth.
Conclusion: Investigate Evidence with Relentless Perseverance
Being innocent is not enough to exonerate a wrongful conviction; one must also have a spirit of relentless perseverance. Because evidence that science cannot test today may perhaps be testable by science ten years from now. Missing evidence may simply be hidden in someone's drawer and will appear once time passes and things change. Lying witnesses may eventually confess the truth one day, unable to bear the condemnation of their conscience. So many "maybes" are all opportunities to exonerate wrongful convictions. As long as one's will is firm and one never gives up, one will surely be able to wait for the day when the truth finally comes to light.
This article is an AI-generated translation of the original Chinese text. In the event of any discrepancy, the Chinese version shall prevail.