Police are looking into the possibility that more unsolved crimes might be linked to a 56-year-old man surnamed Lee, who has been identified as a prime suspect in cold case rape-murders from the 1980s and early 1990s.

Police said Tuesday that there might be another set of rapes involving Lee, who is already a suspect in at least eight rape-murders that took place between 1986 and 1991 in Hwaseong, Gyeonggi Province. Police tied Lee to the case after DNA evidence from three of the rape-murders matched his in a recent forensic analysis.

The Gyeonggi Nambu Provincial Police Agency, which is leading the probe, said seven rapes reported between February and July 1986 in Hwaseong bear similarities with the serial rape-murders, the first of which occurred Sept. 15 that year.

A connection between the two series of crimes was first proposed by criminologist Oh Yoon-sung of Soonchunhyang University in a 2011 study.

Oh told The Korea Herald the suspect’s modus operandi -- or crime methods and habits -- of tying victims with clothes they were wearing and putting underwear over their heads appears to be identical in the serial rapes that preceded the five-year sequence of rape-murders.

Oh said the rape victims’ descriptions of the perpetrator’s appearance fit the suspect. He also noted the coincidence of two serial cases occurring in the same city and year.

“We cannot rule out the possibility that the rapes and the serial murders might have been committed by the same guy,” Oh said.

On Tuesday, a team of nine seasoned profilers visited Busan Prison for the fourth time to question Lee, who is already serving time over a different conviction. Lee was sentenced to life in prison in 1995 for the rape and murder of his sister-in-law.

There was no admission of guilt, police said. Lee consistently denied all allegations in the first three rounds of questioning last week.

In a Sept. 19 press briefing, the police agency vowed all-out efforts to crack the 33-year-old cold case despite the statute of limitations having expired. Police credited new DNA technology for leading them to a suspect.

By Kim Arin (arin@heraldcorp.com)