Who Made the Evidence Lie?

After a man surnamed Hsu recently confessed to being the actual perpetrator in the wrongful execution of Chiang Kuo-Ching, public criticism focused on the military justice system's longstanding disregard for human life. What received less attention was that Chiang's case had also undergone extensive forensic examination: there was an autopsy report, DNA testing, and crime-scene reconstruction, all used to support the military court's conviction. Chiang's exoneration shows that evidence itself may not lie, but the forensic experts who "make the evidence speak" can still get the evidence badly wrong-or present it misleadingly.

Hsieh Sung-Shan, then director of the Taipei City Police Department's forensic center and one of the people who personally examined the Chiang case, wrote in a 2004 article that the evidence collected at the scene and the reconstruction-including semen testing on tissue paper-could be connected to establish the suspect's conduct; that bloodstain-pattern reconstruction corroborated the confession and the reenactment of how the girl was killed; and that examination of the wounds and the autopsy resolved the family's doubts about inconsistencies between the alleged weapon and the wounds, and between the time of death and the confession. The article presented the police forensic work, forensic pathology, and DNA analysis as reliable. In light of what we now know, those claims demand a basic question: how did they become so wrong? 

Forensic Examination Depends on Professional Conscience

Take the DNA analysis. The original conclusion-"the possibility that the sample contains the defendant's DNA cannot be excluded"-is logically compatible with saying "the presence of the defendant's DNA cannot be established." Yet those two formulations can push a criminal case in radically different directions, even toward life or death. The examiner's judgment and professional conscience therefore matter enormously. In 1996, when this case occurred, DNA testing had only recently been introduced in Taiwan. The HLA-DQα typing method then in use required visual interpretation of a colorimetric strip and had relatively low discriminating power, around 17%. The way an examiner characterized the result was especially important. But Taiwan's forensic institutions were government agencies, and most examiners were police officers or civil servants. That institutional position could encourage forensic personnel to confirm the theory already adopted by investigators and prosecutors rather than test it independently.

The danger is even greater when investigators first identify a suspect and only afterward ask forensic personnel to examine the evidence. In this case, the bloodstain-pattern reconstruction performed under Hsieh's direction supposedly "confirmed" the truth of Chiang Kuo-Ching's confession and reenactment. In retrospect, it looks less like scientific reconstruction than an effort to fit the evidence to a confession already obtained. The weapon examination by the Armed Forces Forensic Center was more myth than science.

Other wrongful-conviction cases from roughly the same period also involved erroneous DNA interpretation, including the Lu Chin-Kai and Chi Fu-Jen cases; cases such as Hsu Tzu-Chiang and Hsiao Yang-Lung involved confessions extracted through torture. Their underlying problems resembled those in Chiang's case. The tragedy is that Chiang Kuo-Ching did not, like Su Chien-Ho and his two co-defendants, encounter a Minister of Justice willing to halt an execution long enough for the truth to be tested. Now that the truth has emerged, compensation to the family is not enough. We also need to ask who made the evidence "lie," and why, so that the same tragedy is not repeated.