For years, critics of Rep. Ilhan Omar, D-Minn., have raised questions about her marriages and made the explosive claim that she had married her brother.

As Omar has become a frequent target of attacks by President Donald Trump, allies of the president have only ramped up their criticism of the congresswoman, who was a refugee and is now a naturalized U.S. citizen of Somali descent.

Trump himself mentioned the allegation that Omar had married her brother on July 17. Talking to reporters before boarding Marine One, Trump said, "There's a lot of talk about the fact that she was married to her brother. I know nothing about it."

Several media outlets, including the Associated Press and her hometown paper, the Minneapolis Star-Tribune, have delved into this question and Omar’s personal history.

In a June 23 article, the Star-Tribune wrote that it "could neither conclusively confirm nor rebut the allegation that he is Omar’s sibling." That echoed the conclusion by Snopes.com in February 2019, that "the evidence uncovered thus far isn’t definitive enough to come down on one side or the other." PolitiFact was unable to reach a conclusion during the 2018 election cycle.

The Star-Tribune has published the most detailed, evidence-based reporting. Here are some of the key points from their report:

• In 2002, Omar, then 19, religiously married Ahmed Hirsi, but not legally. Omar and Hirsi had two children, but in 2008, they obtained a religious divorce. The following year, in 2009, Omar married Ahmed Nur Said Elmi both religiously and legally.

Little is known about Elmi, other than that Omar has referred to him as a "British citizen" and that he attended high school in the Minneapolis area and, like Omar, later attended North Dakota State University.

• In 2011, Omar and Elmi divorced religiously, but remained married legally. In 2012, Omar and Hirsi reconciled and had a third child. In 2017, Omar legally divorced Elmi, and the following year, she legally married Hirsi.

• In 2016, as Omar was seeking a state House seat, the conservative website AlphaNewsMN, followed by other ideological sites, posted a screenshot of an Instagram post — since deleted — that was allegedly uploaded by Elmi on June 12, 2012, shortly after Omar gave birth to her third child. The caption of the photograph identified Elmi as holding the baby girl, calling her "nieces." To some, this suggested a sibling relationship.

• Omar has denied the allegation that Elmi is her brother — she has called the charges "disgusting lies," the AP reported — but has not provided further documentation to debunk it. She did tell the Star-Tribune in October 2018, before she was elected to Congress, that "it’s really strange, right, to prove a negative. … If someone was asking me, do I have a brother by that name, I don’t."

• In June 2019 a different problem emerged for Omar: During an investigation of alleged misuse of campaign funds by Omar, a Minnesota campaign finance board determined that Omar had filed joint tax returns with her future husband, Hirsi, at a time when she was legally married to Elmi.

Omar’s office referred PolitiFact to the response it provided to the Star-Tribune, which says in part: "Ilhan has shared more than most public officials ever do about the details of her personal life — even when it is personally painful. Whether by colluding with right-wing outlets to go after Muslim elected officials or hounding family members, legitimate media outlets have a responsibility not to fan the flames of hate. Continuing to do so is not only demeaning to Ilhan, but to her entire family."

On July 18, PolitiFact interviewed Kevin Diaz, the Star-Tribune politics editor who oversaw the article co-bylined by reporters J. Patrick Coolican and Stephen Montemayor.

Here is our conversation with Diaz, lightly edited for space and clarity.

Why was this something you felt was important to investigate?

My interest as an editor began with the silence she has maintained about her improper tax filings. That got my attention. She would say only that she had corrected the 2014 and 2015 tax filings and would not divulge anything about why she had filed taxes with a man she was not married to when she was separated but still married to someone else. It was a natural question: Who is Elmi and how does he fit into her life? We were not getting a lot of answers.

We also knew that since 2016, when she was running for the legislature, conservative opinion journalists and activists had been hounding her about these allegations, which had actually first surfaced in a local Somali news forum. We wanted to know, what is the case to be made for this narrative that won’t go away? She’s our congresswoman. It was a very provocative allegation. We felt as journalists, if there was smoke, it’s our job to look behind it to see if there’s fire. What’s behind it? What is the evidence?

So I assigned a couple of reporters to go back over the case. It turned out that most of the evidence behind (the notion that she had married her brother) was in social media. So we looked at the social media trail. It had been wiped clean, and that piqued our interest even more. But because the posts had been wiped, we had to rely on screen grabs that had been posted by people who we know have an ax to grind. So it was tricky.

Were these social media posts the main evidence for the allegation that she had married her brother?

As far as I can tell, it’s really only the social media posts. It seemed clear that there is some kind of personal relationship between Omar and Elmi. But whether they are family or not, we can’t tell. We weren’t able to come close to determining whether that was the truth. And frankly, we were wary of drawing any conclusions.

They both went to North Dakota State University, and they had overlapping addresses. Our public records searches determined that in at least one period after she married Elmi, all three (Omar, Elmi and Hirsi) used the same address in Minnesota. It raises questions about the nature of the relationship if she is living with both the person she’s married to and her eventual husband.

What’s really made it hard is that she’s been unwilling to address any of these questions. That has fueled the controversy. We quoted her at length to say that these were mere accusations, that they were unfair, and that she shouldn’t have to address them. Be that as may, there was an undisputed instance of her filing her taxes improperly. And if you’re in Congress, you should explain that to your constituents.

It’s true that for many immigrants like Omar, there are not a lot of available public records from their home country. That works both for and against her. It can leave family relationships murky. But in fairness to her, these allegations can be hard for her to disprove.

How much time did your staff spend researching the story?

From start to finish, a couple of weeks. They were covering multiple daily stories during that time, too. I have a team of six political reporters and I put two of them on the story. Our paper had been accused of neglecting the story earlier, and I felt like we owed it to our readers.

It wasn’t easy — there just isn’t a lot of evidence to mine in this area. There are some public records searches we could do and a social media trail, but not a lot of hard documentary evidence unless she’s willing to share them.

How much cooperation did you get from Omar?

It came up when she was running for Congress last year. One of our reporters confronted her about it last October. She did not show us the immigration records we asked for, only a photo of them on a cellphone.

We’ve asked her these questions, and also asked her to make her father available. We’ve tried to reach Elmi. We’ve tried to reach her sisters. Her family could put this (the question of Elmi’s relationship to Omar) to rest easily. No one will talk to us. I wish we could send a reporter to Mogadishu (Somalia) but we don’t have the bandwidth.

What kind of reaction have you had since the most recent story came out?

We have been slammed by both sides. On the left, people are saying, "Why are you dignifying these unproven allegations?" To which I reply, "Look at the tax filings — it would be journalistic negligence if we didn’t try to find out what’s behind it."

On the right, the complaint has been that we did too little, too late: "This has been the story for years — where have you been?"

Since the article came out, no one has come forward with smoking-gun, decisive proof that would make it look like we missed something. You see circumstantial evidence that begs for some kind of explanation from a member of Congress, but there’s no smoking gun that she married her brother.