SEOUL, South Korea — A 56-year-old man has confessed to raping and murdering 14 women more than two decades ago, the South Korean police said on Wednesday, as they closed in on the man who they believe is the culprit in the country’s most infamous serial killings.

Lee Chun-jae emerged as a prime suspect in the killings after the police revealed last month that his DNA matched samples taken from at least four of nine killings that took place in Hwaseong, south of Seoul, between 1986 and 1991.

Mr. Lee has since confessed to investigators that he not only committed all nine murders but also raped and killed five other women in Hwaseong and nearby cities, Ban Gi-soo, a senior police investigator, said during a news conference on Wednesday. Separately, Mr. Lee also confessed to 30 rapes or attempted rapes, Mr. Ban said.

For decades, the Hwaseong serial murders have spawned such fear among South Koreans that they became the best-known cold cases in the country. The victims, ranging in age from 14 to 71, were strangled to death after their mouths were stuffed with their stockings, bras or socks. Some of the bodies were mutilated with umbrellas, forks or razor blades.