In this July 1993 file photo, authorities in Hwaseong, south of Seoul, investigate a rape and murder believed to have been done by a serial killer.
Seoul CNN  — 

A South Korean man has confessed to the murder of 14 women including nine who were victims in the country’s most infamous serial killing case – but the suspect won’t face prosecution, police said.

Last month, police said they believed they had identified the man behind at least three of 10 killings which took place in Hwaseong, a city south of Seoul, between 1986 and 1991.

On Friday, a police official told CNN a man had confessed to nine of the killings. He also confessed to an additional five murders and about 30 sexual assaults. One of the 10 Hwaseong deaths is now believed to be a copycat murder, the official said.

The man – who is in his 50s – is already in prison serving a life sentence, according to police.

Nine criminal investigators worked to build rapport with the suspect – and last week his attitude changed, according to the official from Gyeonggi South Provincial Police Agency.

The suspect gave a detailed confession, even drawing an explanation of locations involved in the killings on a piece of paper, the official said. Police will now work to verify whether the confession is true, and cross-reference it against their original investigation records.

Despite the confession, the suspect won’t face charges over the killings as South Korea’s statute of limitations on the most recent of the cases ran out in 2006.

Although police knew that prosecution wasn’t a possibility, they kept records of their investigations and continued making checks into the cases.

“Naturally, the police must investigate the crimes,” the police official said. “It is an important case that had prompted questions all over Korea.”

“The victims and their families had strongly demanded (the truth). No matter how much time has passed, uncovering what really happened is the reason police exist.”

Seoul-based criminal attorney Kim Gwang-sam told CNN that it would not be possible for the families of victims to take a civil suit either. In South Korea, civil cases must be taken within 10 years from the time of the crime, he said.

Infamous murders

For decades, authorities were unable to solve the string of murders.

The killings are infamous in South Korea, and were even the subject of a 2003 true crime film “Memories of Murder” by top South Korean director Bong Joon-ho, who became the first Korean to win the prestigious Palme d’Or this year for his movie “Parasite.”

Although the killings remained unsolved, there was evidence that they could be linked.

All of the nine victims were sexually assaulted and murdered, and most were strangled to death, an official from Gyeonggi Nambu Provincial Police Agency told CNN. In many of the cases, a piece of their clothing such as stockings or a blouse was used in the killing.

The victims ranged in age from young teenagers to women in their 70s.