Story highlights Unnamed employee left a note apologizing for "causing controversy"

He admitted to deleting data, but added the NIS didn't spy on local people before the 2012 election

Seoul (CNN) An employee of South Korea's National Intelligence Service (NIS) has been found dead alongside a suicide note apologizing for "causing controversy," according to South Korean police.

The body of the unnamed employee, thought to be in his 40s, was found on Saturday in his own car, which was parked on a mountain near Hwasan-ri, near the city of Yongin, south of Seoul.

Preliminary investigations have concluded he died of carbon monoxide poisoning from the burning of charcoal.

In a press briefing Sunday, Yongin Dongbu police Chief Park Ki-young revealed the man left a note identifying himself as an NIS employee and confessing to deleting data relating to counterterrorism and North Korean surveillance.

The handwritten note also included reference to persistent speculation that the government spied on its own citizens in the lead up to the 2012 election. According to police, the author said: "There was really no investigation on local people and (the) election."

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