The hacker who broke into the Democratic Party's computer systems two years ago has reportedly been outed as a Russian intelligence agent.
The Daily Beast reports the agent's identity was revealed when he briefly forgot to turn on his VPN (virtual private network), leaving behind a trace of his location - the headquarters of Russia's GRU intelligence agency in Moscow.
VPN services allow internet users to hide their true location.
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The hacker, who used the name Guccifer 2.0, had previously claimed to be a Romanian who broke into the Democrats' computers "on a lark", reports the Daily Beast.
Special Counsel Robert Mueller is reportedly looking into the revelations as part of the probe into alleged Russian meddling in the US election and whether the Trump campaign colluded with them.
The Daily Beast also reports Trump campaign adviser Roger Stone claimed to be in touch with Guccifer 2.0 in 2016.
Guccifer 2.0 began leaking contents of the Democratic Party's server not long after the breach was publicly revealed.
Mr Trump has denied collusion with Russia to disrupt the 2016 US election. US intelligence agencies believe Russia interfered through social media and fake news articles to tip the election in Mr Trump's favour.
Intelligence agencies also believe the hackers got access to the Republican Party's computers, but chose not to leak anything.