Rudy Giuliani accused Biden of interfering in a Ukrainian investigation for political gain. Giuliani may have done exactly that in 2017.

• A top US diplomat suggested in congressional testimony that President Donald Trump's personal lawyer, Rudy Giuliani, is connected to Ukraine's decision to freeze its investigation into Paul Manafort in 2017.
• The Washington Post first raised the possibility last week and said Trump's and Giuliani's quid pro quo with Ukraine this year may not have been the first of its kind.
• A timeline of key events in June 2017 shows Ukraine dropped its Manafort investigation days after Giuliani met with top government officials.
• After the investigation stalled, Ukraine's president at the time, Petro Poroshenko, secured a White House meeting with Trump.
• The Trump administration also finalized a sale of anti-tank missiles, called javelins, within days of the Manafort case being dropped.
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The Washington Post's David Ignatius raised a troubling possibility in a column last week: what if President Donald Trump's and Rudy Giuliani's apparent quid-pro-quo with Ukraine this year may not have been the first of its kind?

On Monday, Congress released a transcript of the testimony of a top US diplomat who suggested the same possibility.

On June 7, 2017, Ignatius pointed out, Giuliani traveled to Ukraine and gave a speech to the Victor Pinchuk foundation. While he was there, Giuliani met with the president at the time, Petro Poroshenko, and the top prosecutor, Yuriy Lutsenko.

While Giuliani was visiting, Ukraine's anti-corruption bureau was in the middle of a criminal investigation into a "black ledger" of allegedly illegal payments made by Ukraine's pro-Russia Party of Regions. Among the recipients of those payments was Paul Manafort, the former chairman of Trump's campaign who was forced to resign when the public became aware of his shady financial dealings.

It's unclear what Giuliani discussed with Poroshenko and Lutsenko when he went to Ukraine. But two days after their meeting, the investigation into Manafort was handed off from the anti-corruption unit to Lutsenko's office.

The move meant the investigation was effectively stalled and, as one former Ukrainian official told The Kyiv Post, it meant "that somebody gave an order to bury the black ledger."

Fast forward 11 days from when the investigation came under Poroshenko's control: On June 20, 2017, Poroshenko got his first White House meeting with Trump, an event the Ukrainians had been working toward securing since January of that year but that only came to fruition after Ukrainian investigators halted their probe into Manafort.

Perhaps more importantly, as The New York Times reported last year and Ignatius noted in his column, the Trump administration was also in the middle of finalizing plans to sell anti-tank missiles, called javelins, to Ukraine at the time its investigation into Manafort was effectively frozen. The weapons sale to Ukraine eventually went through.

Here's a condensed version of the timeline:

• Ukraine was investigating Manafort for corruption and shady financial dealings in 2016 and 2017.
• On June 7, 2017, Giuliani traveled to Ukraine and met with Poroshenko and Lutsenko.
• On June 9, the investigation into Manafort was placed under Lutsenko's and Poroshenko's control and was effectively frozen.
• On June 20, Poroshenko got a long-sought after White House meeting with Trump.
• Around that time, the Trump administration signed off critical military aid to Ukraine.

If this sounds familiar, it's because the events bear similarities to Trump's and Giuliani's effort this year to urge Ukraine's new government, led by President Volodymyr Zelensky, to deliver political dirt on former Vice President Joe Biden ahead of the 2020 election.

While the pressure campaign was ongoing, the US was withholding a nearly $400 million military-aid package to Ukraine.

The president maintains that there was no quid pro quo and that he didn't hold up the aid to force Ukraine to give him information that would personally benefit him. But Mick Mulvaney, the acting chief of staff, confirmed last month that Ukraine pursuing political investigations was part of Trump's decision to temporarily freeze the aid.

Bill Taylor, the US's chief envoy in Ukraine, also testified to Congress that Gordon Sondland, the US's ambassador to the EU, told him "everything" - meaning military aid and a White House meeting for Zelensky - depended on Ukraine acceding to Trump's demands.

The Trump administration released the aid on September 11, two days after it learned of a whistleblower's complaint against Trump that accused him of abusing his power and soliciting foreign interference in the upcoming election.

On Monday, Congress released the transcript of testimony that Marie Yovanovitch, the US's former ambassador to Ukraine, gave as part of the ongoing impeachment inquiry into Trump.

Yovanovitch also suggested a link between Giuliani and the black ledger investigation involving Manafort.

She testified that Arsen Avakov, the Ukrainian Minister of the Interior, spoke to Giuliani in February about Biden and the 2016 election and subsequently warned Yovanovitch it would be "dangerous" for Ukraine to get into domestic US politics.

When a lawmaker asked Yovanovitch why Avakov tied Giuliani to Ukraine getting involved in the US, she said it related to the issue of the black ledger.

Referring to that investigation, Yovanovitch testified that Avakov told her it was dangerous for Ukraine to get involved to look at "how did all of that come about; the issue of whether, you know, it was Russia collusion or whether it was really Ukraine collusion, and, you know, looking forward to the 2020 election campaign, and whether this would somehow hurt" Biden.

Asked whether Giuliani and his associates' interest in Biden came up during her conversation with Avakov, Yovanovitch testified, "Yeah, I mean looking backwards to what happened in the past, with a view to finding things that could be possibly damaging to a presidential run" by Biden.