Rudolph W. Giuliani has made a habit of working with Ukrainian politicians of questionable repute in his search for information to help President Trump. And even as Trump is on the verge of being impeached over the whole thing, Giuliani was in Ukraine again on Thursday, meeting with yet another one.

The story behind this one, though, is particularly dark.

Andriy Derkach is an independent member of Ukraine’s parliament who has caught Giuliani’s eye by pushing for his own government to investigate former vice president Joe Biden’s son Hunter Biden. As Time magazine reports, though, Derkach hasn’t really produced any information suggesting actual wrongdoing, and he hasn’t gotten much traction.

Derkach’s name is a big one in Ukraine. A story about him might have even helped sparked that country’s 2004 Orange Revolution. That story involved a murder plot that implicated his father.

The story is from 2000, and it suggested the younger Derkach could be the “Ukrainian Putin.” At the time, that label — a reference to Russian President Boris Yeltsin’s handpicked successor, Vladimir Putin — was applied to a number of potential successors to President Leonid Kuchma.

Derkach said he was “highly irritated” by the label, according to a transcript of an interview with a local weekly magazine published by the BBC. The source of his irritation wasn’t because it was then a comparison to a strongman; No one knew at the time what Putin would make of his power over the following decade or so. Derkach did not want to be seen as having presidential ambitions.

Kuchma didn’t appear to appreciate the article either. The online journalist Kuchma pegged as being behind it, Georgiy Gongadze, had been very critical of him.

According to the English-language Kyiv Post, later-released recordings that allegedly captured Kuchma and his top aides featured them discussing the article and what to do about Gongadze. One of those aides just happened to be Derkach’s father, Leonid Derkach, who was the head of Ukraine’s security services.

According to Andrew Wilson’s book “Ukraine’s Orange Revolution,” here’s what the recording — which Kuchma claimed was of him but had been doctored — showed them discussing on June 12, 2000:

KUCHMA: This Gongadze, right?
KUCHMA: You can take care of him?
LEONID DERKACH: The time for him to mouth off will come to an end. I’ll crush this f---er.

In later conversations, they spoke more explicitly about organizing Gongadze’s abduction. Another aide said to “take [Gongadze] to Georgia and dump him there,” to which Kuchma responded, “The Chechens should kidnap him and ask for a ransom!” The man identified as Kuchma would return to the Chechen idea in another recording.

Gongadze would soon claim he was being followed, and by September he was killed, his headless body discovered in a forest near Kyiv in November. Soon after, the above recordings, which had been made by an security service officer named Mikola Melnichenko who fled the country, were released.

They sparked protests calling for Kuchma’s ouster. Kuchma would survive it, but his governing coalition collapsed, and he was forced to fire Leonid Derkach. Some consider the protests to have set in motion the Orange Revolution of 2004, in which the demonstrations forced a redo of an allegedly corrupt election won by Kuchma’s chosen successor. The new election resulted in the election of a pro-Western leader, Viktor Yushchenko.

Even Yuschenko’s government would struggle to provide accountability for Gongadze’s killing. In 2005, a Ukrainian parliamentary commission labeled Kuchma, Leonid Derkach and two other senior officials as being the masterminds of the plot. One of the other two, former interior minister Yuri Kravchenko, had been found dead of an alleged suicide earlier that year.

Three police officers were convicted in 2008. Kuchma was charged in March 2011, but the charges were dropped later that year. A top aide to Kravchenko, Olexey Pukach, was convicted in 2013 and is still appealing his life sentence.

The elder Derkach, a former KGB officer, was never charged with wrongdoing. Now his son, who attended the Dzerzhinsky Higher School of the KGB in Moscow and formerly belonged to a pro-Russian political party, is working with Giuliani to try to affect another major election This one is in the United States, four years after the real Putin interfered in one.