New details have emerged about the Government Integrity Fund, a non-profit dark money group that has spent over $1 million on pro-GOP ads in the U.S. Senate race in Ohio.

As ProPublica first reported Friday, the chairman of the group is Tom Norris, a Columbus lobbyist who employs a former aide to Josh Mandel, the Republican challenging Sen. Sherrod Brown in the race. The former aide, Joel Riter, also has an office in the same building as the Government Integrity Fund on East State Street in Columbus.

Riter had declined to comment on any role with the Fund, telling us last week, “I’m not going to comment on any kind of involvement I have with anyone.”

But in a story published after our report, the Associated Press quoted William Todd, the lawyer for the Fund, as saying that Riter is “involved (with the nonprofit) a little bit here and there” — such as running errands. Norris, Riter, and Mandel’s campaign all did not respond to requests for comment.

A reporter who visited the address for ProPublica on Monday found no one from the Fund in the building. Another tenant said he had not seen anyone from the group in some time.

Meanwhile, in an interview in Akron over the weekend with Ohio public radio station WKSU, Mandel denied any coordination with the Government Integrity Fund. “Our campaign does not coordinate with any outside groups,” Mandel said. Under federal election rules, outside groups and campaigns are not supposed to coordinate.

In an interview with WDTN, the NBC affiliate in Dayton, Mandel said of Riter, “I have not talked to him for a very long time.” Asked whether Riter is involved with the Fund, Mandel said, “I have no idea, you’d have to ask them.”

Huffington Post noted that since the ProPublica story was published, a line was removed from Riter’s LinkedIn page detailing his employment at Norris’ firm, Cap Square Solutions. Here is the old version of Riter’s LinkedIn page.

In an interview with ProPublica last week, Riter said that he is still a lobbyist for Cap Square. Huffington Post also noted that Riter’s location on the LinkedIn page has changed from Columbus to Alexandria, Virginia.

The Brown campaign has seized on the connections between Mandel and the Government Integrity Fund, putting out a mock resume for Riter on Monday.

Exactly who is putting up the money for the Fund’s ads remain secret because it is a non-profit group that does not have to report donors.

Additional reporting by Jackie Storer.