It didn’t matter that Daniel Romanowski tried to warn a clerk he might be ineligible to vote. It didn’t matter that the clerk registered him anyway. It didn’t matter that Romanowski left the box on the voter registration form asking if he was a citizen blank.

To Sebastian Kielmanovich, an assistant U.S. attorney in North Carolina, all that mattered was Romanowski, a Polish immigrant who has held a green card since 2004, voted in two presidential elections and wasn’t a citizen of the United States.

He should have known better, Kielmanovich told a federal judge earlier this month, according to a transcript of the sentencing hearing HuffPost obtained. He should be punished.

The judge agreed. He sentenced Romanowski, who pled guilty to illegal voting, to a year of probation. His sentence included two months of house arrest and a $1,200 fine to be paid out in $100 monthly installments.

Romanowski is one of about 20 legal immigrants being prosecuted for illegally voting in the 2016 election in North Carolina. Many of the incidents appear to be mistakes and misunderstandings, a form filled out incorrectly, a mistaken poll worker. In addition to a criminal sentence, the immigrants could also be deported.

The cases were organized by Robert Higdon, the U.S. Attorney for the Eastern District of North Carolina, a President Donald Trump appointee. So far Higdon’s office has obtained plea agreements from about half of the defendants charged.

He sent one defendant, an American citizen, to prison for accidentally helping her immigrant boyfriend to vote, and he issued a $200 fine to an Italian green card holder who came to the U.S. as a teenager in the 1980s. All of the other defendants have been sentenced to combinations of probation and a fine.

Individuals in the group are receiving sentences on an ongoing basis.

Sen. Mazie Hirono (D-Hawaii) and some lawyers question why Higdon has chosen to use scarce prosecutorial resources to pursue these cases when there are more serious crimes in need of attention. And that scrutiny has further intensified amid a scandal in Higdon’s jurisdiction that revealed absentee ballot fraud benefitted a Republican in a congressional race last year.

In an era when President Trump regularly spreads conspiracy theories about voter fraud in the U.S., HuffPost is closely tracking the cases because they underscore what it looks like when prosecutors pursue voter fraud in an aggressive manner.

Higdon’s office declined to comment to HuffPost and a spokesperson pointed to news releases on the office’s website.

“The right to vote is a precious privilege available only to citizens of the United States,” he said last month after Denslo Allen Paige was sentenced to two months of prison time and a $250 fine for helping her boyfriend, a non-citizen, to register to vote. Even though she had worked as a pollworker, she said he had no idea he was eligible to vote.

“When a non-citizen votes in a federal election it serves to dilute and devalue the vote of American citizens and places the decision making authority of the American electorate in the hands of those who have no right to make those choices,” Higdon’s office said after Paige was sentenced.

Most of the cases receiving sentencing hearings, it appears, were misunderstandings and mistakes made by voters and poll workers. But in February, during a sentencing hearing for Juan Francisco Landeros-Mireles, a Mexican immigrant who has been a lawful permanent resident since 1990, Kielmanovich voiced another concern.

Kielmanovich said he was alarmed by a poll worker who appeared to ask Landeros-Mireles which party he intended to vote for in the 2016 presidential election, something poll workers are not supposed to do.

“He was asked if he was going to vote Republican or Democrat, and he responded, ‘Para la señora,’ which means in Spanish ‘for the lady.’ Kielmanovich said in court, according to a transcript obtained by HuffPost.