(CNN) - With the release of a new television ad Friday, Republican Sen. Scott Brown of Massachusetts is not letting up in reminding voters of a controversy involving Elizabeth Warren's claim to Native American heritage.
The new ad, "Got Caught," features interviews with people criticizing the Democratic Senate candidate for listing herself in faculty directories as having Native American heritage while teaching at Harvard Law School.
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"Harvard touted her as a minority," one woman says in the ad. "Initially she said she didn't know anything about it. She kept on covering it up and going deeper and deeper into the hole."
While Warren said she listed herself under that category to meet others with similar backgrounds, critics have argued she tried to use minority status as a way to advance her career. The Crimson, Harvard's student newspaper, printed articles in the late '90s quoting law school administrators hailing Warren's Native American heritage as evidence of faculty diversity.
The New England Historic Genealogical Society provided CNN with initial research showing several members of Warren's maternal family claiming Cherokee heritage. The Native American link extends to Warren's great-great-great grandmother O.C. Sarah Smith, who is said to be described as Cherokee in an 1894 marriage license application. The genealogical society gathered that information through a 2006 family newsletter and said the original application cannot be located.
"Professor Warren got caught in a lie," one man says in the ad. "We already have enough people in Washington that will say anything. Don't need one more."
Friday's 30-second spot marks the latest development in what's been a weeklong focus on the issue. Earlier this week, video showed some of his staff members mocking Warren's claim by making "war whoops" and "tomahawk chops" at a recent rally.
The principal chief of the Cherokee Nation called the gestures "offensive and downright racist" in a statement, saying the actions "perpetuate negative stereotypes and continue to minimize and degrade all native peoples."
Asked about the tape Tuesday at a press availability, Brown said he hadn't seen the footage but did not support the actions as described by reporters.
"That's not something I condone. It's certainly something that if I am aware of it, I'll tell that member to never do it again," Brown said.
On Monday, the senator's team put out an ad compiling newscasts reporting on Warren's claims. The ad, designed to cast doubt on Warren's trustworthiness, ends with a reporter asking Warren if there is anything that will "come out about you that we don't already know."
"I don't think so, but who knows," Warren responds.
Warren fired back in an ad of her own, saying Brown was attacking her family.
"As a kid, I never asked my mom for documentation when she talked about our Native American heritage," Warren says in the spot. "What kid would? But I knew my father's family didn't like that she was part Cherokee and part Delaware, so they had to elope."
"Let me be clear. I never asked for or never got any benefit because of my heritage," she continues, addressing the central concern that Brown has brought up on the campaign trail and at the candidates' first debate last week. "The people who hired me have all said they didn't even know about it."
- CNN's Ashley Killough and Kevin Liptak contributed to this report.