Hackers linked to North Korea’s military intelligence agency were found to be responsible for extorting ethereum cryptocurrency worth 58 billion won ($41.5 million) back in 2019, according to the National Office of Investigation of the Korean National Police Agency, Thursday.

According to the KNPA, North Korea’s state-sponsored hacker groups Lazarus and Andariel were found to be involved in the theft of 342,000 ethereum tokens from the South Korea-based cryptocurrency exchange Upbit in November 2019.

While the tokens were valued at 58 billion won at the time, they are now worth roughly 1.47 trillion won at today's valuations.

Though the police did not release details regarding the methods used in the hacking attacks due to concerns about recurrence and copycat crimes, officials said they confirmed North Korea’s involvement by tracking IP addresses and cryptocurrency flows with the help of the US Federal Bureau of Investigation.

The KNPA added that up to 57 percent of the stolen assets were laundered at 2.5 percent below the market price through three cryptocurrency exchange websites -- presumed to be made by the North -- in exchange for bitcoin. The remaining ethereum assets were laundered through 51 different overseas exchanges.

Police officials also confirmed that some of the stolen assets, converted into bitcoin, were discovered on a Swiss cryptocurrency exchange. After proving to Swiss prosecutors that the bitcoin in question was part of the assets stolen in South Korea, 4.8 bitcoin were successfully returned to Upbit -- an amount currently worth around 600 million won.

Although this is the first time a South Korean investigative agency has confirmed North Korea’s involvement in cryptocurrency hacking crimes, similar charges have already been raised in the past by the UN and other countries.

Back in July, a crypto exchange in India was reportedly targeted, resulting in damages worth $200 million. Around the same time, cryptocurrency valued at $35 million was also stolen from a Japanese exchange, with Lazarus being identified as the culprit behind both hacks.

In May, the UN Security Council's sanctions panel stated that it suspects North Korea was responsible for up to 97 cyberattacks in which virtual assets worth $3.6 billion were stolen from cryptocurrency companies between 2017 and 2024.

North Korea has repeatedly denied its involvement in hacking and crypto heists.