Roh Hoe-chan, a three-term lawmaker of the left-leaning Justice Party had been under investigation for allegedly receiving 50 million won ($44,300) from a powerful political blogger linked to many top politicians.
The blogger, widely known by his online nickname “Druking”, is currently on trial for using illegal hacking programmes to sway public opinion on Naver, the South’s top online portal.
“Druking” is accused of artificially increasing the number of positive responses — the equivalent of Facebook’s “Like” function — to tens of thousands of online comments on Naver that attacked or supported politicians or political parties in a bid to win personal favours.
In a suicide note left in a Seoul apartment, Roh admitted he had received money from the blogger, but denied he had offered any favour in return, the Yonhap news agency said.
He had been expected to be summoned soon by prosecutors for questioning.
South Korea has one of the world’s highest suicide rates, and suicides of public figures — from politicians to businessmen — embroiled in humiliating scandals make frequent headlines.
Late former president Roh Moo-hyun, who served from 2003 to 2008, shocked the nation in 2009 when he jumped off a cliff while being investigated over a corruption scandal.