CHICAGO (CBS) — Russian intelligence officials used an Illinois computer as part of an operation to hack Democratic Congressional Campaign Committee documents, according to a federal indictment released Friday.

That detail is part of a larger grand jury indictment of 12 Russian intelligence officers for hacking-related offenses in the 2016 election, the Justice Department announced Friday. The DOJ says the Russians intended to interfere with the 2016 presidential election, and all 12 defendants are members of the GRU, a Russian intelligence agency.

ilinois in indictment 2 Russian Agents Used Illinois Computer To Hack Dems In 2016, Indictment Alleges

The indictment says the agents transferred stolen Democratic Party documents to the GRU-leased Illinois computer in April, 2016. A few days later that computer was used to steal additional documents from DCCC and Democratic National Committee files, the indictment alleges.

During the hacking attempt, the agents looked for various files, emails, passwords and fund-raising documents. In one case, they searched documents ofr keywords such as “hillary” “trump” and “cruz” and copied files contained in a folder called “Benghazi Investigation,” the indictment alleges.

Agents also attempted to infiltrate state and county boards of elections, the indictment states. In one case, the agents in July, 2016 hacked an unidentified state board of election database, and stole information about 500,000 voters. The information included names, emails and partial social security numbers.

While the indictment does not name the state board, Illinois election officials acknowledged in August of that year that their database was hacked, but downplayed the impact and did not identify the alleged hackers.

Officials at the time said “no more than about 200,000” voters had been affected by a cyber-hacking of the registration rolls.

The indictment — which comes days before President Donald Trump holds a summit with Russian President Vladimir Putin — was the clearest allegation yet of Russian efforts to meddle in American politics.

U.S. intelligence agencies have said the interference was aimed at helping the presidential campaign of Republican Donald Trump and harming the election bid of his Democratic opponent, Hillary Clinton.

Contributing: Associated Press