An employee of South Korea's National Intelligence Service (NIS) spying agency has been found dead in his car after apparently taking his own life on a mountain road, police say.
His death comes as a scandal over phone-hacking gathers pace.
The man left a suicide note admitting that he had deleted important information about the hacking.
It has emerged that mobile phones were tracked and monitored just before the presidential election in 2012.
Government and NIS officials have denied opposition claims that the spyware - bought from an Italian company - was used to monitor South Koreans in general.
They insist that its purpose was to boost the country's cyber-warfare capabilities against North Korea.
The BBC's Stephen Evans, in South Korea, says that the note left by the dead man implies that phones were monitored only to keep tabs on people connected to North Korea and not to besmirch opponents of the right-of-centre president.
The spy agency had a scandalous reputation in the years before South Korea embraced democracy in the 1980s, and was involved in abductions and killings.
The modern NIS is not accused of such serious offences but has nevertheless been embroiled in several scandals, including election meddling.
Opposition politicians allege that it is not politically neutral, breaks the law and is a political tool for sitting presidents.
Last week the Supreme Court ordered a review of the conviction of former NIS head Won Sei-hoon, who was sentenced to three years in jail in February for trying to influence the results of the 2012 presidential election.
