Joe Scarborough's brother supported Trump - until he tweeted this about Joe

George Scarborough, the brother of MSNBC "Morning Joe" host Joe Scarborough, is demanding an apology from President Donald Trump after he alluded to a conspiracy theory about a staffer's tragic death.

What did Trump do that upset the Scarboroughs?

Trump tossed a twitter missive at Scarborough Wednesday morning referencing a conspiracy theory about a staffer who died in his office while he was a congressman.

"So now that Matt Lauer is gone when will the Fake News practitioners at NBC be terminating the contract of Phil Griffin?" the president tweeted, referring to the president of MSNBC.

"And will they terminate low ratings Joe Scarborough based on the 'unsolved mystery' that took place in Florida years ago?" he added. "Investigate!"

What is the "unsolved mystery"?

Trump appeared to be referring to the death of Lori Klausutis in 2001 from an accident. The 28-year-old was found dead in the Florida office of then-Congressman Scarborough, but her death was ruled an accident caused by a fall where she hurt her head. A heart condition aggravated a clot in her brain.

Some conspiracy theorists have speculated that there was a cover-up and that Scarborough was somehow involved in her death. Trump inaccurately referred to it as an "unsolved mystery."

What did George Scarborough respond?

He said that he had been a supporter of Trump in the past but that the tweet had offended him greatly and he wanted an apology from the president.

"Outrageous reference re @JoeNBC where [President Trump] just crossed the line with me."

"I need to see a public apology to my brother Joe or else he has lost my support for good," he added, "which is saying a ton given all the support I’ve shown him in past 2 years."

In another tweet he concluded, "A bold lie by [President Trump] referring to [a] #FakeNews report about my brother [from] 20+ years ago that has put a huge emotional drain on my family, & particularly [Joe Scarborough], crossed the line 'Big Time.'"