A robocall that used an AI voice resembling President Joe Biden’s to advise New Hampshire voters against voting in the state’s presidential primary has been linked to a pair of Texas-based telecommunications companies, the state’s attorney general announced on Tuesday.

New Hampshire Attorney General John Formella, in a news conference on Tuesday, said the source of the calls were linked to two businesses: Life Corporation and Lingo Telecom. Formella identified Walter Monk as the owner of Life Corporation.

Formella said the investigation is ongoing and suggested it involves additional entities other than Life Corporation and Lingo Telecom. He did not say who, or what entity, was ultimately behind the disinformation campaign and the creation of the AI audio. No charges have been filed, Formella said.

“We have issued a cease-and-desist letter to Life Corporation that orders the company to immediately desist violating New Hampshire election laws. We have also opened a criminal investigation, and we are taking next steps in that investigation, sending document preservation notices and subpoenas to Life Corporation, Lingo Telecom, and any other individual or entity,” Formella said.

Formella said that the robocalls numbered in the “thousands,” though he offered a wide range of 5,000 to 25,000.

The calls were made ahead of New Hampshire’s presidential primary in January, urging New Hampshire voters not to vote in the contest and instead “save” their vote for the November election.

“Republicans have been trying to push nonpartisan and Democratic voters to participate in their primary. What a bunch of malarkey,” says the digitally altered Biden voice in the call. “We know the value of voting Democratic when our votes count. It’s important that you save your vote for the November election. We’ll need your help in electing Democrats up and down the ticket. Voting this Tuesday only enables the Republicans in their quest to elect Donald Trump again.”

Biden’s campaign at the time said the it had been referred to the attorney general, and slammed the call as disinformation.

Formella on Tuesday called the case “unique,” saying it offered a “real-life example” of the emerging threat posed by AI.

“I think this case is unique in that it is providing us a real-life example of an attempt to use AI to interfere with an election. That’s been something that we’ve been concerned about in the law enforcement for a while, and it’s certainly something that state attorneys general have talked about. But we had not seen as concrete of an example as this, days before a primary, an attempt to use AI to interfere with an election or to mislead voters,” he said.

Formella also said that other unnamed entities potentially had relevant information about the robocalls, though he declined to share specifics.

“I’m not going to give you an exact number but I can say it’s beyond the two – it’s beyond Texas Life Corporation, Walter Monk, and Lingo Telecom. There are other entities that we think have relevant information, and I would not be surprised if we discover additional entities or individuals beyond those that we have discovered up to this point,” he said.

Biden campaign manager Julie Chavez Rodriguez commended Formella in a statement on Tuesday.

“Disinformation aimed at suppressing voting and deliberately undermining free and fair elections is an unacceptable threat, and we commend the New Hampshire Attorney General for taking the matter seriously and moving swiftly as a powerful example against further efforts to disrupt democratic elections,” she said.

The fake audio was created using an AI voice creation tool named ElevenLabs, according to two separate analyses by the security company Pindrop and by digital forensic experts at University of California, Berkley.