AP Atlanta-based State Government Team reporter Christina Cassidy broke the news that copies of confidential software for a widely used voting machine had been released publicly during an event held by supporters of former President Donald Trump, leading to wider concerns about election security.

After a local elections clerk in Colorado leaked confidential information about her county’s voting machines, Cassidy began calling her sources to get a sense of what the breach could mean for other states that used the same voting machines produced by Dominion Voting Systems. Her source reporting uncovered yet another leak, this time in a county in Michigan where Trump allies had challenged his election loss. The software copies ended up being distributed publicly at a symposium hosted by the CEO of MyPillow, Mike Lindell, a major Trump supporter who has helped spread his lies of election fraud.

The software leak from Antrim County, Michigan, had not previously been reported until Cassidy learned of it. Election security experts said taken together, the leaked software copies could provide hackers with a “practice environment” to probe for vulnerabilities in Dominion machines, which are used in 30 states.

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A worker passes a Dominion Voting Systems ballot scanner while setting up a polling location at an elementary school in Gwinnett County, Ga., outside of Atlanta, Jan. 4, 2021.

AP Photo / Ben Gray