A Virginia man is heading to prison after he attempted to register deceased and nonexistent individuals to vote for Democrats in the 2016 election.

Andrew Spieles, 21, of Harrisonburg, Va. pled guilty Monday in the U.S. District Court for the Western District of Virginia and will serve a prison sentence of 100 to 120 days, CBS affiliate WTVR reported.

Spieles worked for Harrisonburg Votes, an organization affiliated with the Democratic Party, when he attempted to commit voter fraud, according to acting United States Attorney Rick A. Mountcastle.

"In July 2016, Spieles' job was to register as many voters as possible and reported to Democratic Campaign headquarters in Harrisonburg," a U.S. Attorney's Office spokesperson said. "In August 2016, Spieles was directed to combine his registration numbers with those of another individual because their respective territories overlapped. After filling out a registration form for a voter, Spieles entered the information into a computer system used by the Virginia Democratic Party to track information such as name, age, address, and political affiliation. Every Thursday an employee/volunteer hand-delivered the paper copies of the registration forms to the Registrar's Office in Harrisonburg."

Spieles falsified the forms he submitted to the Registrar's Office. He used information from deceased individuals, or added incorrect middle names, birth dates, and social security numbers.

"Spieles later admitted that he prepared the false voter registration forms by obtaining the name, age, and address of individuals from ‘walk sheets' provided to him by the Virginia Democratic Party, fabricating a birth date based on the ages listed in the walk sheet, and fabricating the social security numbers," the spokesperson said. "Spieles admitted that he created all 18 fraudulent forms himself and that no one else participated in the crime."

The vigilance of a Registrar's Office employee put a stop to Spieles' efforts. Someone at the office notified police after an employee recognized a name on a registration form—the deceased father of a Rockingham County Judge.

"The Registrar's Office discovered multiple instances of similarly falsified forms when it reviewed additional registrations" and "learned that the individuals named in these forms had not in fact submitted the new voter registrations," according to the spokesperson.

The incident with Spieles occurred during an election in which fraud was a topic of debate. Following his election, President Donald Trump received criticism for his unsubstantiated claims that he lost the popular vote because "millions" of people voted illegally.

Trump launched a commission last month to review potential voter fraud and voter suppression.

Incidents of fraud and attempted fraud have been reported, and issues with voter registration are a common concern in many U.S. states.

In response, many local governments are taking steps to overhaul voter registration. Washington, D.C. Mayor Muriel Bowser (D.) announced last month a plan to spend $3 million to remove the names of dead people and "other errors" from voter rolls.