polygraph

Du Peiwu Murder Case (杜培武故意杀人案)

The defendant/exoneree 

  • Du Peiwu (杜培武), born in 1967; he was a police officer at the Kunming Public Security Bureau at the time of the incident.

Facts

  • On April 20, 1998, Du Peiwu’s wife and another police officer, Wang, were found shot dead in Wang’s vehicle. The investigating police suspected that Du’s wife and Wang were having an affair and that Du killed them for revenge.

  • On April 22, 1998, Du was detained and interrogated. He confessed after 70 days of interrogation.

  • In June 2000, after Du’s conviction, a group of gang members were arrested for a series of robberies. One of the gang members, Yang Tianyong (a police officer), confessed that he committed the crime in Du’s case. Following Yang’s instruction, the police found the handgun in the drawer of Yang’s apartment, which was linked to the shots that killed the two victims in Du’s case.

  • Both Du and Yang were police officers before they were convicted.

  • The handgun used to shoot the two victims was not found during Du’s investigation.

Procedural history 

  • Du Peiwu was charged with intentional murder of his wife and another police officer.

  • On February 5, 1999, Du was originally convicted and sentenced to death by the Kunming Intermediate Court in Yunnan Province.

  • On October 20, 1999, the Yunnan Provincial High Court confirmed the conviction but changed the sentence to death with two years suspension.

  • On July 6, 2000, Du was exonerated by the Yunnan Provincial High Court because the real perpetrator Yang Tianyong came forward and was convicted.    

Date of the conviction

February 5, 1999

Date the wrongful conviction was reversed

July 6, 2000

Days incarcerated

814

Why was the case reopened/reversed 

On June 17, 2000, the police arrested a group of gang members who had committed serial armed robberies in Kunming City. Yang Tianyong, one of the gang members, confessed that this group also committed the crime in Du’s case and laughed at the police’s incompetence in Du’s case. Later, the police discovered the handgun which was used to shoot the two victims and a mini-recorder belonging to one of the victims was found in a drawer in Yang’s home.

Factors contributing to the wrongful conviction

False confession

  • The police interrogated Du Peiwu for 70 days, including periods of 10 days consecutively and 20 days consecutively. Consistent with Chinese law, lawyers were not allowed to be present during the police interrogation.

  • Du was severely physically and mentally tortured by the police. Du was deprived of sleep, beaten by the police using their fists and electric rods. The police officers tied Du’s hands and hung Du against a door in the air. Du claims that he confessed to stop the torture.

Problematic forensic evidence

  • The mud found on Du’s shoes and pants did not match the mud on the brake plate and gas plate on the vehicle.

  • There were two contradicting reports based on a dog sniffing test concerning whether Du had been in the vehicle where the victims were found.

  • Du also underwent two polygraph tests. The results did not positively show that Du was lying on major issues, but it also did not show that Du was not lying at all. The polygraph expert failed to explain the possible error and inaccuracy in the polygraph tests.

Prosecutorial errors

  • The procuratorate suppressed evidence that proved Du was tortured.

Defense lawyer's errors/absence

  • None. Du was represented by counsel and claimed his innocence.

Court's errors

  • Failed to credit the physical evidence (Du’s shirt which was torn during torture) Du presented at court, as well as Du’s in-court statement, that he was tortured. Refused to credit Du’s in-court exculpatory statements.

  • Failed to consider exculpatory witness identifications and testimonies: No eye witness identified Du as the perpetrator.

Other developments

  • Two police officers in Du’s case were convicted of extorting confession through torture after Du’s acquittal.

  • In October 2001, Du was rewarded RMB 91,141 State compensation by the Yunnan Provincial High Court.

Information sources

Nian Bin Poisoning Case (念斌投放危险物质案)

The defendant/exoneree 

  • Nian Bin (念斌), born in 1976

Facts

  • Nian and the Ding family were neighbors, both running their own small grocery stores independently. They had similar inventories. In the evening of July 26, 2006, a customer bought cigarettes from the Ding family. On the evening of July 27, 2006, the Ding family (1 adult and three children) and the Chen family (2 adults), were poisoned while eating dinner. Nian helped to call the ambulance and to close the Ding family’s grocery store. The Ding’s two children died after they were sent to the hospital. Nian was detained on August 9, 2006, because he “looked suspicious.” The police later reasoned that Nian was a business competitor with the Ding family, and that Nian was motivated to take revenge on the Ding Family because the day before the crime, Ding sold a pack of cigarettes to a customer who originally came to Nian’s store for business. 

  • The police originally investigated a man who was living upstairs from the Dings right after the case was reported. The police found rat poison in four packs and a bottle in this man’s room. This man did not get along with the Ding family and had time to commit the crime. During the interrogation, the man was so nervous that he fainted.

  • The police disclosed that the rat poison found from the man upstairs contains tetramine.

Procedural history 

  • Nian Bin was charged with the crime of poisoning hazardous substance. On February 1, 2008, he was originally convicted and sentenced to death by the Fuzhou Intermediate Court of Fujian Province.

  • On December 31, 2008, the Fujian Provincial High Court remanded this case for retrial upon Nian’s appeal, citing insufficient evidence and unclear facts.

  • On June 8, 2009, the Fuzhou Intermediate Court retried this case and sentenced Nian to death again.

  • In April 2010, the Fujian Provincial High Court affirmed the conviction and sentence, and submitted the case to the Supreme People’s Court (SPC) for death penalty review.

  • In April 2011, the SPC remanded the case back to the Fujian Provincial High Court for retrial on the grounds of insufficient evidence and unclear facts.

  • On May 5, 2011, the Fujian Provincial High Court remanded this case to the Fuzhou Intermediate Court for retrial again on the grounds of insufficient evidence and unclear facts.

  • On November 24, 2011, Nian, again, was convicted and sentenced to death by the Fuzhou Intermediate Court. Nian appealed again to the Fujian Provincial High Court.

  • On August 22, 2014, after nine hearings, the Fujian Provincial High Court exonerated Nian.    

Date of the conviction

February 1, 2008

Date the wrongful conviction was reversed

August 22, 2014

Days incarcerated

2,935

Why was the case reopened/reversed  

  • During the eight years of litigation, Nian, his family and his lawyers insisted that Nian was innocent. Nian’s lawyers kept providing evidence to disclose the questionable investigation process by the police, including evidence of police torturing Nian. They also found third-party toxicologists to overturn the police’s forensic lab conclusion, and discovered flaws and contradictions in the facts and evidence in various police reports.

  • Nian’s case has been highly publicized and Nian’s innocence has been believed and supported by lots of people. This put pressure on the authorities.

Factors contributing to the wrongful conviction

False confession

  • Nian was severely tortured by the police. He was also threatened that if he did not confess, his wife would be arrested. Unable to bear the torture any longer, Nian had tried to commit suicide by biting off his tongue.

Flawed police investigation

  • One police officer appeared at quite a few interrogating sites at different locations questioning different persons at the same time.

  • The police altered witnesses’ written testimony in respect to the source of water the Ding’s family used to cook their supper at the night of the poisoning.

  • The police edited the video record of Nian’s confession during interrogation.

  • When the police first arrived at the crime scene, they concluded that the time of the crime was between 1:40 pm to 6 pm on July 27, 2006.  During this time, Nian had an alibi. The police later changed the time of the crime to the midnight of July 26, 2006.

Problematic forensic evidence

  • The police did not disclose the result of the forensic tests on the food the victims ate and the substance in the victims’ stomach. The police forensic lab reports only show that there was no fluoroacetate in the victims’ stomach and liver, but that it was in their blood and urine.

  • The police’s forensic evidence shows that fluoroacetate was found in the vomit in the trash bin, in the water pot and the cook pan, and one of the dozen door handles at the crime scene.

  • Toxicologists from the defendant’s side reviewed all the police documentation and concluded that the evidence used by the police cannot prove that fluoroacetate had ever been used.  

  • The police did not find fluoroacetate at Nian’s place.

  • Nian did not pass the police polygraph test.

Prosecutorial errors

  • Failed to supervise the illegal and unethical conduct of the police.

Defense lawyer's errors/absence

  • None. Nian was represented by a lawyer who defended his innocence.

Court's errors

  • The court refused to accredit Nian’s in-court statement, which was exculpatory. It did not exclude illegally gathered evidence. It refused to admit any new evidence and kept imposing the same conviction and sentence to Nian at retrials

Other developments

  • After Nian’s acquittal, the same police bureau launched another investigation of him for the same crime. Presently, the police refuse to issue Nian a passport on the ground that Nian is still a suspect for this crime.

  • On February 15, 2015, Nian won his State compensation case for over 1.13 million RMB.

  • Nian’s case was addressed in the 2014 annual report of the Supreme People’s Court.

Information sources