Update: This four-year-old issue has sprung up again, as Donald Trump continues to reference it during his war of words with Sen. Elizabeth Warren (D-Mass.). Asked about Warren's criticisms of him on Monday, Trump referred to her as "the Indian? You mean, the Indian?" The comment followed Warren suggesting Trump was an authoritarian and a "loser." But it wasn't the first time Trump dredged up the old controversy over Warren's heritage.

Given the passage of time, we figured folks might want a refresher. The below is from September 2012.

Sen. Scott Brown (R-Mass.) and Democratic challenger Elizabeth Warren have spent the last six days trading blows over an issue that first emerged in the campaign nearly six months ago: Warren’s heritage.

If you’re just tuning in, here’s a summary of the spat: Warren claims she has Native American ancestry. She’s never substantiated her claim with documentation, saying she learned of her background from her family. Warren insists she has never sought to gain a professional advantage because of her heritage. Brown isn’t satisfied. He wants Warren to release personnel records backing her assertion.

The longer version of the story is filled with some twists and turns. Here’s a look at how it has unfolded:

In late April, the Boston Herald reported that in the 1990s, Harvard Law School – where Warren began  teaching in 1992 and was granted tenure in 1995 – touted the Democrat’s Native American background as part of an effort to boost its diversity hiring record. Warren’s campaign said she didn’t bring up her heritage before Harvard hired her and that her background came out through later conversations.

The next week, Warren acknowledged listing herself as a minority in a directory of law professors. The directory included her on a list of minority professors from 1985 to 1996, the Boston Globe reported. Warren said she listed herself as a minority because she wanted to connect with “people for whom native American is part of their heritage and part of their hearts.” Brown, meanwhile, went on offense, calling for more scrutiny.

In late May, the Globe reported that Warren acknowledged that at some point after she was hired by Harvard and the University of Pennsylvania, she informed the schools of her Native American heritage. The revelation spurred a new round of questions, since Warren never brought up the fact a month earlier, instead saying she didn’t know why Harvard listed her as Native American. Earlier in the May, a report pointed out that she listed herself as “white” at the University of Texas Law School, prompting questions about consistency.

Throughout it all, Warren struggled to get past the story. Her responses to questions about why she identified as Native American were convoluted (and included a discussion of “high cheekbones” at one point).

And Brown’s campaign piled on, seeking to raise more questions about whether Warren used her claim to Native American heritage to her professional advantage. They continue to do so, citing the fact that Warren stopped listing herself as a minority in the faculty directory in 1995 -- the year she received tenure at Harvard -- in a recent press release.

Brown has repeatedly called on Warren to release personnel records to prove she never received professional advantage. She has declined to do so. Officials responsible for hiring her have said her heritage was not a factor in their decision.

Polling conducted after the story received nearly daily coverage in the Bay State’s most prominent media outlets for about a month showed – somewhat surprisingly – that Warren was largely unharmed by the scrutiny her heritage received. Brown’s camp chalked the numbers up to being outspent on TV by the Democrat. For Warren, much of May was spent on defending herself and the heritage debate was still a distraction from her message, if not a clear negative in the polls.

Over the summer, the quarrel simmered, and the near daily back-and-forth slowed. Brown didn’t touch the issue in TV ads, opting instead to run positive spots featuring his signature pickup truck. Warren didn’t highlight the issue, either.

That all changed last week.

In the opening minutes of their first debate, the candidates were asked about each other’s character. Brown quickly brought up the issue of Warren's heritage.

“Professor Warren claimed she was a Native American, a person of color -- and as you can see, she is not,” Brown said at the debate. “I didn’t get an advantage because of my background,” rebutted Warren.

It didn’t end there. On Monday, Brown released his first TV ad raising the topic. The 30-second spot used TV news clips about Warren’s heritage. Warren responded with her own ad later on Monday, in which she once again repeated that she never received any professional advantage due to her background.

On Tuesday, a video showing individuals making war whoops and tomahawk chop gestures outside a rally reportedly included Republican staffers and an aide to the senator, forcing Brown to play some defense. He said he did not condone the actions. The principal chief of the Cherokee Nation called on Brown to apologize.

The weeks ahead will show whether the whole thing has done Warren serious damage at the polls in November or whether Brown's decision to press the issue could backfire on him. But this much is clear: During a cycle when the economy has dominated nearly every competitive statewide race, the nation’s fiscal state has taken a back seat (for a while at least) to a very different issue in one of this year’s most competitive contests.