"While we cannot comment on the specifics of an ongoing investigation, I can confirm that the Democratic Party of Georgia is under investigation for possible cyber crimes", Candice Broce, spokeswoman for the secretary of state's office, told the Atlanta Journal-Constitution.
She explained she tracked down Ms Abrams' mobile phone number and called her to say she wanted to offer assistance in the final days of the campaign.
In her remarks at Thursday's town hall with Abrams, Winfrey told the crowd that she is a registered independent, "because I don't want any party and I don't want any kind of partisan influence telling me what decisions I get to make for myself".
Vice President Mike Pence tried to share a fairly typical Republican talking point in Georgia on Thursday, slamming Hollywood and the celebrities visiting the state to support Democrat Stacey Abrams, including Oprah Winfrey and Will Ferrell.
Mr Pence has criticised Ms Abrams for using Ms Winfrey during her campaign. I've earned the right to think for myself.
If Abrams wins next week, the former Georgia state House minority leader would become the country's first female African-American governor.
"You are disrespecting and disregarding their legacy, their suffering and their dreams when you don't vote", she added.
President Trump is holding a rally with Kemp later Sunday in Georgia. I'm not trying to test any waters.
Among that "onslaught", Winfrey blasted Republican ads she'd seen in her hotel room casting Abrams as too radical for the state, calling it "noise...created to confound you with fear".
More than 1.5 million of the state's nearly seven million registered voters have cast ballots already. "This is the South. People have been really wonderful and really optimistic about Stacey Abrams".
"So I'm canvassing for Stacey Abrams".
The Road to Power, a white supremacist and anti-Semitic video podcast hosted by Scott Rhodes of Idaho, is the group behind the robocall.
Interesting position, because local Republicans have, from time to time, touting a tax credit that has turned Georgia into a film-making force; the industry contributed an estimated $2.7 billion in direct spending in Georgia a year ago, according to a report in the Atlanta Journal Constitution.