Police say they've identified a suspect in a three-decade-old South Korean serial murder case. But he won't face charges

Investigators in July 1987 examine the scene in Hwaseong, south of Seoul, where a woman was raped and brutally killed.

Seoul (CNN)Beginning more than three decades ago, 10 women died in a spate of killings in the same South Korean city.

For years, authorities were stumped by what local media has called the worst serial murder case in the country's modern history.
But in a press briefing Thursday, South Korean police said they believed they had identified the man behind at least three of the killings which took place in Hwaseong, a city south of Seoul, between 1986 and 1991.
The alleged suspect, who police did not name, is in his 50s and is already in prison where he is serving a life sentence, according to CNN affiliate KBS. A police official for the Gyeonggi Nambu Provincial Police Agency confirmed to CNN that the man is in his 50s, but declined to provide any further details.
    But the suspect won't face charges over the killings, as South Korea's statute of limitations on the cases ran out in 2006.
    Despite the statute of limitations running out, police maintained records of their investigations and continued making checks into the cases, Ban Gi-Soo, the director of the Hwaseong serial murder investigation team, said Thursday.
    In July, police asked the national forensic service to test DNA which had been taken from the scenes, Ban said. "We were notified that there is a suspect whose DNA matched the DNA found in evidence from three scenes," he said. Police are continuing their investigations, he said.
    The murders are famous in South Korea where they are known as the "Hwaseong serial killing case." On Thursday, the case was trending on Naver, South Korea's largest search engine.

    Brutal killings

    Although police have only connected the suspect to thre