Who Was Capt. Humayun Khan – and Why Are His Parents Feuding with Donald Trump?

Republican presidential nominee Donald Trump is in the midst of a polarizing new feud, with Khizr and Ghazala Khan, the grieving parents of Muslim U.S. Army Capt. Humayun Khan, 27, who was killed in a suicide bombing in Iraq in 2004.

As the controversy continues to escalate this week, get caught up with this quick blow-by-blow of what's been said.

Thursday:
• On the final night of the Democratic National Convention, Khizr gave a moving tribute to his son in which he denounced Trump's proposal to ban Muslims from entering the U.S. as unconstitutional. Holding up a pocket copy of the Constitution on stage, Khizr – a Harvard-educated lawyer who became a United States citizen after emigrating from Pakistan in 1980 – asked Trump, "Have you even read the U.S. Constitution? I will gladly lend you my copy."

Friday:
• In an interview with MSNBC's The Last Word, Khizr shared a "second half" of his speech, aimed at Congress. He called on Senate Majority Leader Mitch McConnell and Speaker of the House Paul Ryan to repudiate Trump, saying, "This is a moral imperative for both leaders to say to him, 'Enough. You are about to sink the ship of the patriot Republicans.' "

Saturday:
• A $1 pocket version of the U.S. Constitution made the Top 10 bestselling books list on Amazon.com.

• Trump first responded to Khizr's speech in an interview on ABC's This Week, in which he suggested that Khizr's wife, who stood silently by his side during his speech, was forbidden to speak as a Muslim woman. "Maybe she wasn't allowed to have anything to say," Trump said.

Trump also responded to Khizr's comment that the real estate mogul has "sacrificed nothing and no one," saying, "I think I've made a lot of sacrifices. I work very, very hard. I've created thousands and thousands of jobs, tens of thousands of jobs, built great structures. I've had tremendous success. I think I've done a lot."

Sunday:
• Ryan and McConnell released statements distancing themselves from Trump's attacks on the Khan family – but neither mentioned the candidate by name.

• The Washington Post published an op-ed by Ghazala in which she said she was still too overcome with grief to speak about her son at the convention. "Walking onto the convention stage, with a huge picture of my son behind me, I could hardly control myself," she wrote. "What mother could?" But, she wrote, "… without saying a thing, all the world, all America, felt my pain. I am a Gold Star mother. Whoever saw me felt me in their heart.

• Trump took the feud to his favorite forum, Twitter, saying Khizr "viciously attacked" him at the convention.

• Trump's running mate, Indiana Gov. Mike Pence, released a Facebook statement attempting to defuse the situation.

Monday:
• Khizr and Ghazala made the rounds on morning news shows, again slamming Trump for his "derogatory remarks" about Muslims, while also saying they "want to be out of this controversy." "We don't want to continue. That is not our style. We are a decent, dignified family of this country, very appreciative of the blessings that we have enjoyed ... this is not our path," Khizr said.

• Trump responded on Twitter during the live interview.

• Arizona Sen. John McCain issued a statement condemning Trump's comments about the Khans and saying the nominee does not represent the Republican party.

"In recent days, Donald Trump disparaged a fallen soldier's parents," said McCain, a war hero who himself has been criticized by Trump for being captured during the Vietnam War. "He has suggested that the likes of their son should not be allowed in the United States – to say nothing of entering its service. I cannot emphasize enough how deeply I disagree with Mr. Trump's statement. I hope Americans understand that the remarks do not represent the views of our Republican Party, its officers, or candidates."