“WE WORK in the shadows to protect the sunlit land.” So ran the founding motto of South Korea’s most secretive agency, the National Intelligence Service (NIS), tasked with foiling North Korean plots. Recently other branches of government have been exposing the shadows to a little sunlight. Earlier this year massive protests led to the impeachment of the president, Park Geun-hye, who was found to have abused her authority for personal ends. Prosecutors investigating how far the rot went have discovered that successive directors of the NIS had been delivering bags of cash to Ms Park on a regular basis. Two have been arrested, pending trial; a third has been questioned.

All deny wrongdoing. Although they admit to handing over the money, they say they thought it was for some legitimate, if unknown, purpose. The payouts came from the NIS’s “special activity funds”. This money is set aside for classified operations, and is disbursed at the discretion of the director. Prosecutors say that between 2013 and 2016, 4bn won ($3.7m) left the coffers of the NIS, some of it going into Ms Park’s pocket via two close aides, and some to allies (including Choi Kyung-hwan, a former finance minister, whose office was raided this week). The allegations add to the roster of corruption charges against Ms Park, whose impeachment centred on her collusion with a friend to extract payouts from big companies.

Nam Jae-joon, the spy chief who started the payments (pictured with Ms Park on the next page), claimed in court that he was told to send the money when he first took the job (although he forgets by whom). Lee Byung-ho, who was his successor, says he received a “personal” order from Ms Park.

Prosecutors will struggle to find evidence that the money was given in exchange for a favour, as the law on bribery demands. They faced a similar problem when trying to establish that the 43bn won that Lee Jae-yong, the vice-chairman of Samsung, gave to associates of Ms Park was a bribe. Although he was eventually convicted of paying a smaller inducement, of 8.9bn won, Mr Lee still insists that Ms Park extorted the money from him. He is appealing the verdict.

This is not the first time the intelligence agency has been accused of grotesque abuses. In its first incarnation, under Park Chung-hee, a military dictator and the father of Ms Park, it tortured pro-democracy activists. Since then it has changed names twice and tried to reform its image. But its reputation took a more recent hit when it was found to have hired as many as 30 teams to conduct an online smear campaign against left-leaning politicians during the presidential election in 2012, including the liberal candidate, Moon Jae-in.

Mr Moon went on to win this year’s snap election after Ms Park was removed from office, and has pledged to “clean up” official abuses. Won Sei-hoon, the director of the NIS from 2009-13, was jailed earlier this year for orchestrating the online campaign. Mr Moon’s party, Minjoo, has introduced a bill to reform the NIS. It would change the agency’s name yet again and take away its authority to investigate breaches of national security, limiting it strictly to gathering intelligence. But Mr Moon’s attempt to make the NIS into a “Korean-style CIA” is unpopular with conservatives, who see the agency’s investigative abilities as a powerful tool against North Korean infiltration.

Prosecutors will soon visit Ms Park in her cell to quiz her about the payments from the NIS. As the investigation drags on and politicians squabble over reforms, cynicism is setting in. A local television channel recently aired a report on the NIS’s history of makeovers. The tagline read: “Storefront changed, role identical”.