Presidential candidate U.S. Sen. Bernie Sanders speaks during a news conference in December about police reform and preventing people of color from being victimized by police officers. (Photo: Joshua Lott/Getty Images)

The dustup over a data breach that briefly erupted in the Democratic presidential primary last week isn’t over as far as Sen. Bernie Sanders, I-Vt., and his team are concerned.

In a conversation with Yahoo News, a top Sanders campaign adviser made a series of explosive allegations about how the Democratic National Committee (DNC) and a political technology company that works with the party handled the incident. According to the Sanders adviser, the DNC and NGP VAN, a firm that has a contract with the party organization to operate a voter file, have responded to the data breach by “leaking information” and “stonewalling an investigation” into the matter.

“We have demanded a full investigation from top to bottom,” the Sanders adviser said.

Sanders’ adviser noted that a lawsuit the campaign filed in federal court about the data breach last Friday, Dec. 18, is still ongoing, and described it as an attempt to get answers despite the party’s lack of cooperation.

According to a blog post published by NGP VAN, the data breach occurred on Wednesday, Dec. 16. The company said it involved a “bug” in the software NGP provides to the DNC. NGP VAN software is used by the DNC to operate a massive file of voter data that is shared by the party and all of the Democratic presidential campaigns. Both campaigns also rely on NGP to store their private files. The data in the shared and private files is essentially the lifeblood of a modern presidential campaign. It includes information vital to campaigns’ day-to-day organizing and strategy, including potential supporters they are targeting and how many voters they expect to turn out in key primary states.

Because of the software issue, members of the Sanders campaign were able to access information that belonged to Hillary Clinton’s campaign. On Dec. 17, news of the incident broke and the Sanders campaign announced it had fired its national data director, Josh Uretsky, for taking advantage of the breach to access data belonging to Clinton. The top Sanders adviser told Yahoo News one of the remaining concerns is that Uretsky was recommended to the campaign by people with ties to the DNC and NGP VAN.

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Sen. Bernie Sanders’ campaign manager, Jeff Weaver (right), talks to reporters in December. Sanders’ campaign was disciplined by the DNC after a software error enabled a staffer to review Hillary Clinton’s private campaign data. (Photo: Chip Somodevilla/Getty Images)

“It’s not as if we conjured this guy Josh from thin air. This is an individual … who was recommended to us by the DNC and NGP VAN,” the adviser said.

According to the adviser, one of the references that Uretsky gave when he applied to work with the campaign was the DNC’s National Data Director Andrew Brown, who works closely with the shared voter file program.

“Andrew Brown spoke to us and gave him a positive review, as did this guy Bryan Whitaker,” the adviser said.

The adviser identified Whitaker as the COO of NGP VAN. Whitaker is no longer with the company. His LinkedIn page lists Whitaker as having left the firm for a job at another political data company in August of this year. Uretsky’s LinkedIn says he began working on the Sanders campaign in September.

Brown and Whitaker did not respond to requests for comment on this story. A spokesperson for the DNC declined to comment.

The Sanders adviser described the fact Uretsky was recommended to the campaign by people with links to the DNC as astonishing in light of what happened. Specifically, the adviser pointed out that the campaign was slammed by Clinton’s team for the breach and punished by the DNC.

“I just think it’s utter hypocrisy on their part,” said the adviser. “I mean here we are being attacked for the behavior of an individual, which we ultimately fired. We agree he acted improperly, but it’s just amazing to me that this … individual that actually caused this trouble in our campaign was recommended by these guys.”

Uretsky was not the only person the Sanders campaign disciplined for being involved with the data breach. The campaign announced the suspension of two additional staffers after the Democratic presidential debate last Saturday night. The Sanders adviser did not say anyone other than Uretsky was recommended by people affiliated with the DNC or NGP VAN.

Heading into the debate, the Sanders team was under fire for the breach. The Clinton campaign released several statements to the media describing the incident as theft that was potentially even criminal. It produced audit logs showing multiple Sanders staffers accessed Clinton files on over 20 occasions. The DNC temporarily locked Sanders’ team out of the shared voter file, which contains information that is vital to the campaigns’ day-to-day operations and organizing efforts.

The adviser suggested the DNC and NGP VAN are “ignoring their own responsibility,” arguing that Uretsky’s references from people linked to the party and the company show both the DNC and NGP VAN “bear responsibility” for the incident. The world of progressive political consulting is a small one, and, as in other professions, it’s common for people to provide recommendations for those in their network. Still, given what happened with the breach, the adviser suggested Brown’s recommendation of Uretsky could be evidence of a conspiracy.

“I don’t know how you can more centrally connect this thing than those two entities,” the adviser explained. “Here we are being attacked by both of those entities when, in fact, they recommended this guy to the campaign.”

Lorraine Joseph, right, a student nurse at Broward College, makes a sign supporting candidate Bernie Sanders as Jenny Ellis, left, looks on, in Pembroke Pines, Fla. (Photo: Wilfredo Lee/AP)

Though Sanders’ team has not denied there was wrongdoing by members of its staff, it has objected to the fact Clinton’s team went public with its concerns. Sanders’ campaign also has described the DNC’s decision to close it out of the shared file as draconian and part of a pattern that shows the party is unfairly working to help protect Clinton’s frontrunner status in the primary.

According to the adviser it was ”outrageous” the Clinton campaign was given the audit logs that it showed to the media and Sanders’ team was not. The adviser said these logs were unquestionably given to the Clinton campaign by NGP VAN or the DNC.

“This is one of the things that we were whipsawed in over the course of the, you know, 48 hours,” the adviser said. “NGP VAN was leaking information, clearly provided documents to the DNC and the Clinton campaign — or the DNC was providing those documents to the Clinton campaign. Documents that we didn’t have.”

The adviser said the Sanders campaign was “trying to scramble around and find out what happened” in the immediate period after the breach was revealed. According to the adviser, it was hard to determine the extent of the incident because campaign staffers were locked out of the DNC software and not given the logs. Meanwhile, with the logs in hand, the Clinton campaign was able to make detailed public allegations about improper activity by members of Sanders’ team.

“It would have been fair play to provide us the info in proper time … they basically locked us out and then started throwing stuff under the table,” said the adviser.

Democratic presidential candidate Hillary Clinton speaks during a town hall meeting in Keota, Iowa, in December. (Photo: Charlie Neibergall/AP)

Over the weekend, a Clinton spokesperson told Yahoo the audit logs were believed to have been provided to the Clinton campaign by NGP VAN. When asked about the documents, a spokesperson for NGP VAN pointed out to Yahoo News that the company’s contract for the voter file is with the DNC, which would mean it is not working directly with the campaigns for that software.

The Sanders campaign filed a lawsuit on Dec. 18 demanding that its access to the file be restored. At a press conference announcing that suit, Sanders campaign manager Jeff Weaver described the DNC’s behavior as an effort to “undermine” Sanders’ attempt to mount a progressive challenge to Clinton.

“By their action, the leadership of the Democratic National Committee is now actively attempting to undermine our campaign. This is unacceptable. Individual leaders of the DNC can support Hillary Clinton in any way they want, but they are not going to sabotage our campaign — one of the strongest grassroots campaigns in modern history,” Weaver said.

The campaign was able to reach an agreement with the DNC to have its access to the data restored late on the night it filed suit. NGP VAN’s blog post noted the company played “no role” in making the decision to lock the Sanders campaign out of the file and that its staff worked long hours to quickly restore the campaign’s access following the agreement with the DNC. The Sanders campaign is still working with NGP VAN.

Even after having its access restored, the Sanders campaign did not drop its dispute with the DNC. It has used the situation to appeal for donations and in messages to allies described its dissatisfaction with the party as long simmering. In one note to supporters, Weaver pointed to the fact the DNC has scheduled multiple debates on weekends when television viewership is generally low as evidence the party is improperly helping Clinton.

“The reality is that the huge turnouts that we’ve had at our meetings, our strong fundraising, our volunteer base and quick rise in the polls have caused the Democratic National Committee to place its thumb on the scales in support of Hillary Clinton’s campaign. You see that fact evidenced in their decision to bury the Democratic debates on weekends during nationally televised football games. It’s more or less an open secret,” Weaver wrote.

Both the Clinton campaign and the DNC have dismissed the Sanders team’s arguments about the debate schedule and claimed it is decided by the networks that air the forums.

Hillary Clinton listens as Sen. Bernie Sanders speaks during the Democratic presidential debate in Manchester, N.H., in December. (Photo: Ida Mae Astute/ABC via Getty Images)

At the debate on Saturday, Sanders personally apologized to Clinton for the incident. He also called for “an independent investigation” and blasted the DNC’s decision to lock the campaign out of the voter file as an “egregious act.” Clinton accepted the mea culpa and said she agreed on an independent inquiry. However, the Sanders adviser said the DNC is blocking efforts to review the matter.

“We have demanded a full investigation from top to bottom,” the adviser said. “Hillary Clinton agreed to it in the debate Saturday, and the DNC continues to stonewall a full investigation.”