Volodymyr Zelenskiy, the Ukrainian president, has welcomed a criminal investigation against his predecessor whom he beat in last year’s election. Mr Zelenskiy’s comments refer to a leaked phone call which shows then-President Petro Poroshenko and then-U.S. Vice-President Joe Biden discussing the dismissal of a Ukrainian prosecutor in exchange for U.S. support for an IMF loan in 2015. The heavily edited recording was published on Tuesday by Andriy Derkach, an Ukrainian member of parliament known for a friendly relationship with Rudy Giuliani, a personal attorney for U.S. President Donald Trump in a throwback to last year’s Ukraine scandal that led to impeachment proceedings against Mr Trump. A day after Ukrainian prosecutors launched a formal inquiry into suspected treason by Mr Poroshenko, President Zelenskiy said on Wednesday that it was up to law enforcement agencies to investigate those allegations while voicing support for the probe. “I think (Poroshenko and his allies) were running in the country in such a way that they have a lot of adventures and verdicts ahead of them,” he told a news conference marking his first year in office. Mr Zelenskiy, a popular comedian without any political background, during last year’s election campaign repeatedly accused Mr Poroshenko of corruption and abuse of power, citing recurrent media reports that document possible conflicts of interests and other misdemeanours. Mr Poroshenko has denied those allegations. President Zelenskiy’s declared willingness to go after his former opponent has evoked uncomfortable comparisons to Viktor Yanukovych, a former Ukrainian president who oversaw an investigation that landed his arch-rival Yulia Tymoshenko in jail. The impeachment inquiry against President Trump was triggered by last summer’s phone call with Mr Zelenskiy in which Mr Trump asked the Ukrainian leader to investigate Democratic candidate Biden and his son’s work for a Ukrainian oil company in exchange for U.S. military aid. Mr Zelenskiy has denied that Mr Trump pressured him to look into the allegations that Mr Biden got then-Prosecutor General Viktor Shokin fired because he planned to investigate Hunter Biden’s work in Ukraine. Mr Shokin, who served as Ukraine’s Prosecutor General in 2015-2016, was widely accused of failing to pursue any major anti-corruption investigation, which left Ukraine’s international donors deeply frustrated. Foreign officials as well as Ukraine’s respected anti-corruption activists openly urged for the dismissal of Mr Shokin who never had an active investigation in Hunter Biden’s work.

The first face-to-face meeting between President Trump and top Democrats since the impeachment inquiry began did not go smoothly. The Democrats walked out Wednesday, claiming the president insulted House Speaker Nancy Pelosi during a briefing for congressional leaders on the deteriorating military situation in Syria. Weijia Jiang reports.

More closed-door testimony is scheduled Thursday in the House impeachment inquiry into President Trump. One whistleblower accused President Trump of pushing Ukraine to investigate the Bidens in exchange for military aid. The law firm representing the whistleblower is fighting to keep their client’s identity a secret despite calls from the president and Republicans to reveal it. Alex Wagner, CBS News special correspondent and co-host of Showtime’s “The Circus,” spoke with an attorney at the law firm.

Maryland Rep. Elijah Cummings, a powerful voice among Democrats and chairman of the House Oversight Committee, died early Thursday at a hospital in Baltimore. The 68-years-old had faced a series of health issues. Cummings' committee is one of three leading the House impeachment inquiry. Nancy Cordes reports.

Democrats say they are armed with new evidence in their impeachment inquiry – and this time it comes straight from the president's acting chief of staff and on national television. In a remarkable news conference Mick Mulvaney acknowledged President Trump withheld nearly $400 million in military aid from Ukraine as he demanded Ukraine investigate Democrats. Hours later, he later tried to walk back those words that confirmed a quid pro quo took place. Nancy Cordes reports.

Republican strategist Matt Gorman and Democratic strategist Isaac Wright joined CBSN to break down how Republicans and Democrats have been talking impeachment as we near one month into the inquiry.

Next week, the acting U.S. ambassador to Ukraine is expected to appear on Capitol Hill for questioning in the impeachment inquiry. William Taylor's testimony comes as a growing number of Republicans in Congress struggle to defend the president's actions over Ukraine and Syria. Weija Jiang reports.

This week on "Face the Nation," Margaret Brennan, in Syria, a shaky ceasefire brokered by the U.S. is set to expire Tuesday while the White House continues defends itself against impeachment calls.

From the U.S. working to bring violence to a standstill with a five-day ceasefire, to Democrats pouncing on White House officials as the impeachment process heats up. This was the week that was in Washington.

Congressman Jim Himes, a Democrat on the House Intelligence Committee, says lawmakers need to know who exactly gave the order to withhold military aide to Ukraine.