South Korean police told reporters Monday that information related to the drug investigation into the since-deceased actor Lee Sun-kyun were consistently being leaked, and that officials are looking into how the reports were relayed to outside parties.

Officials have confirmed suspicions that a photocopy of the original investigation report had been leaked, according to the National Office of Investigation's chief, Woo Jong-soo. Gyeonggi Nambu Provincial Police Agency has been probing allegations that Incheon police, which had handled Lee's case, had given the related information to local media outlets.

Investigators raided the Incheon police agency last month to procure evidence, including the cellphones of some officers involved in the drug crime investigation unit and records of the investigation.

"It is yet unclear how (the report) was leaked, if it happened by accident or on purpose, but the Gyeonggi Nambu Provincial Police Agency has conducted a raid and is questioning those involved," he said in a press briefing.

Woo added that the investigation involves a wide range of media outlets that reported details related to the investigation that had not yet been publicized, including local investigative news outlet Dispatch, which has already been raided by police. "The Incheon Metropolitan Police Agency did not reveal details such as dates the deceased was to be summoned, yet the information has been consistently leaked," he said.

No particular individual has been pinpointed as a suspect yet, Woo said.

The death by suicide of Lee in December has sparked nationwide furor regarding how the case was handled by police and media here. His police visits were highly publicized in spite of Lee's requests for them to be kept private, raising suspicions that the dates on which he was to be questioned had been leaked.

Media outlets who reported details of Lee's personal life, including content from his private conversations via a mobile messenger, had also been subject to criticism. Oscar-winning director Bong Joon-ho -- who worked with Lee in the Oscar-winning "Parasite" -- and other prominent figures in the local entertainment scene jointly criticized police and media last month.

Lee, who was 48 years old, was best-known globally for his role as the wealthy patriarch in "Parasite." He had a long career in Korea as a working actor in film and TV dramas spanning over two decades.

The actor maintained until his death that he was tricked into taking drugs and he tested negative in both a reagent test conducted during a police investigation and a comprehensive lab-based drug analysis of hair samples by the National Forensic Service.