South Korean man cleared of killing teenager after spending 20 years in jail for her murder

The high school graduation photo of Lee Chun-jae, left, and a facial composite of the Hwaseong serial killer / Korea Times

Seoul, South Korea (CNN)A man who wrongfully spent 20 years in prison for killing a teenager has been cleared of her murder following a high-profile court case in South Korea that exposed police torture and investigation failures.

Yoon Seong-yeo -- now in his 50s -- was found not guilty Thursday following a retrial in the northwestern city of Suwon over the 1988 rape and murder of a 13-year-old in her bedroom in Hwaseong, then a rural, undeveloped area near the country's capital Seoul.
The teenager was one of 10 killed in the area between 1986 and 1991 in a spate of high-profile deaths known as the Hwaseong murders. Yoon was the only person ever convicted in connection to the killings. He was sentenced to life in prison and ultimately spent 20 years behind bars for the 13-year-old's rape and murder.
    In a verdict released Thursday, judge Park Jeong-je found that police had used torture, including sleep deprivation, and illegal detainment to obtain Yoon's confession to the 1988 murder.
      "As a member of the judiciary, I apologize to the accused, who suffered great physical and mental pain, for the court's failure to function properly as the last bastion of human rights," he said. We sincerely hope that the retrial of this case will be a little consoling and contribute to the restoration of the accused's honor."
      The result means Yoon's name is finally cleared -- more than 30 years after the murder took place. It's also a rare outcome in South Korea, where only a tiny fraction of applications for retrials are accepted, according to experts.
      "I'm relieved that the final ruling found me innocent," Yoon said following the verdict. "I can let down this heavy load I've been carrying for 30 years and get some rest."
        Yoon has claimed his innocence for years, but was only granted a retrial after police made a breakthrough in the case last year.
        In September, police announced that new DNA evidence linked at least some of the Hwaseong murders to Lee Chun-jae, who has been in prison since 1994 for the rape and murder of his sister-in-law. The following month, Lee confessed to all 10 of the murders and another four that police did not provide details on.

        Coerced confession

        At the months-long retrial, Yoon's lawyers argued that their client -- who was a 22-year-old, uneducated repairma