The official story that a top justice official — and key witness in the potential obstruction case against Trump — stepped down just got demolished by Trump's own son.

When it was announced last week that Andrew McCabe, deputy director of the FBI, was immediately stepping down from his position, questions were raised about the circumstances of his departure.

The Trump administration’s position was clear: they wanted McCabe gone. At the behest of Trump, Attorney General Jeff Sessions had reportedly been pushing for McCabe’s firing for months. That’s why many people were suspicious of the sudden and unexpected news that McCabe would be stepping down.

Still, the official story was that McCabe’s departure was voluntary — at least until now.

On Thursday afternoon, Donald Trump Jr. appeared to slip up and accidentally admit that McCabe had, in fact, been fired.

In a tweet that completely contradicts the story that McCabe stepped down voluntarily, Don Jr. said twice that McCabe was fired — destroying the Trump administration’s narrative and raising questions about why Trump’s son is involved in decisions about leadership at the FBI.

Donald Trump Jr tweet 2-1-18

Don Jr. didn’t say who made the call for McCabe to be fired, but it has been widely reported that Trump wanted him gone for months.

As a key witness who could testify against Donald Trump in a potential obstruction of justice case, McCabe has been targeted by a vicious smear campaign led by Trump and his Republican allies.

Sessions was so forceful in pushing for McCabe’s firing that Christopher Wray, Trump’s chosen FBI director, even threatened to resign if McCabe was removed from his position.

Now, it appears as if that’s exactly what happened — and the only reason we know about it is because Don Jr. was so caught up tweeting about a phony memo that he accidentally blurted out more evidence of a cover-up.