A slate of key witnesses told members of Congress what they'd heard and seen firsthand regarding President Trump and the shadow policy for Ukraine aimed at getting concessions from its leaders.

A Pentagon official said Ukraine asked about the military aid on July 25, the day the nations' leaders spoke. It has been assumed that Kyiv wasn't aware the funding was put on hold until much later.

Lawmakers heard from two witnesses called by Republicans, former Ukraine peace envoy Kurt Volker and former National Security Council aide Tim Morrison.

But Tim Morrison, formerly the top Russia official on President Trump's National Security Council, said he found nothing wrong with the July 25 call between Trump and his Ukrainian counterpart.

Yovanovitch said President Trump's comments that things might "happen to her" felt like a "threat" and that her recall shows how corrupt elements can oust a U.S. diplomat.

The State Department staffer who overheard a newly revealed phone call was then told the president cared more about looking into the Bidens than Ukraine policy, the House committee learned.

After weeks of closed-door depositions, Democrats are planning open hearings this week about the Ukraine affair. Here's where the story stands — and what's coming next.

A top White House attorney placed records about President Trump's now-famous Ukraine call in a system few could access, Alexander Vindman testified. His was one of two transcripts released Friday.

A top State Department official, George Kent, told members of Congress that he thought President Trump's Ukraine pressure plan undermined the rule of law and hurt U.S. diplomacy, his transcript shows.

The president's adviser is facing charges that he allegedly lied to Congress and obstructed an official proceeding. Stone has pleaded not guilty and said he has done nothing wrong.

It was an intelligence community whistleblower who brought the matter to the attention of Congress. But insiders also recorded objections about what took place within the administration.

House Democrats building a case against President Trump are looking at obstruction as a possible article of impeachment, and not only in regards to the Ukraine investigation.

Months or more after Democrats began throwing around the I-word, the House formally commits to opening an impeachment inquiry. Meanwhile, more witnesses confirm the Ukraine affair.

Timothy Morrison verified to House investigators that President Trump leaned on Ukraine to launch investigations he thought might help him. He worried about blowback — but not legal implications.

Chief District Judge Beryl Howell rejected the Justice Department's case that the grand jury material must stay secret and Republicans' argument that a vote was needed to launch impeachment.

Attorney General Bill Barr commissioned U.S. Attorney John Durham to look into the early phases of the Russia investigation. Democrats say he is turning the Justice Department into a political weapon.

A key diplomat validated a kernel of the Ukraine affair to House investigators, Ukrainian officials told reporters something critical, and more. Here's what you need to know.

Ambassador William Taylor talked with compatriots in real time about his objections to President Trump's policy. Now he's scheduled to meet behind closed doors with members of Congress.

President Trump commissioned Rudy Giuliani as his top guy for Ukraine, and the White House also appointed "three amigos" to carry out its policy. The administration says nothing's wrong here.

Although new pieces of the puzzle are added all the time, some of the biggest questions about the Ukraine pressure campaign — and what Congress may do about it — aren't yet resolved.