The uncle of Hialeah’s former mayor was arrested Friday as part of a broad voter-fraud investigation, after police say he filled out two absentee ballots with his own choices, not those of the voters involved, including a woman with dementia.

Sergio Robaina, 74, turned himself in Friday afternoon. He was briefly held at Ward D of Jackson Memorial Hospital, where inmates receive medical treatment, before posting a nominal bond Friday evening. His nephew is former Hialeah Mayor Julio Robaina.

Sergio Robaina was charged with two felony counts of voter fraud for allegedly filling out the two ballots in a way that did not match the voters’ intentions. He also faces two counts of violating a county ordinance by possessing more than two absentee ballots belonging to others.

Robaina admitted to police he picked up the ballots of seven or eight other people, according to an arrest affidavit, and told police that “he will continue to do it.”

Robaina is the second ballot broker arrested as part of the investigation, which has brushed the political campaigns of the Miami-Dade mayor and state attorney, and the office of a sitting county commissioner.

Last week, police arrested Deisy Cabrera, 56, who collected at least 31 absentee ballots over two days last month. She was charged with filling out an absentee ballot and forging the signature of a terminally ill woman in a nursing home.

Robaina’s case stems from 164 absentee ballots police say were dropped off at a post office by the woman who ran Miami-Dade Commissioner Esteban Bovo’s Hialeah district office.

Among the ballots were those of a man, identified in the arrest affidavit as G.M., and his mother, identified as O.H., who has dementia. G.M. told police Robaina chose the candidates and then had G.M. and his mother sign the ballots.

“G.M. stated that neither he nor his mother had any input into which candidates were designated on their ballots,” the affidavit says.

The Miami Herald identified the man and his mother as Gustavo Martinez, 45, and Ocilia Hernandez Martinez, 82, based on the 164 ballots reporters viewed at the county elections department Thursday.

Martinez told an El Nuevo Herald reporter Friday that police had asked him about “a friend” of his, Sergio Robaina.

“He’s been pulling scams,” Martinez said. “I had the absentee ballot, and I wanted to vote for certain people, and he said, ‘No no no no no.’ Then he marked the ballot himself for the people he wanted to vote for.”

Martinez, who said he fears fallout for speaking to police, said he did not remember whom he wanted to vote for.

Several other voters whose ballots were among the 164 told reporters Thursday and Friday that they gave their ballots to Robaina, known as “ e l Tío,” or “the Uncle.” People who know Robaina say he has collected absentee ballots for years.

Robaina admitted to a Miami Herald reporter Thursday that he has long collected ballots, but he said he mostly does so for the elderly and infirm.

“I’ve collected ballots because the person can’t,” he said. “They have to be very old or something. And the ballots have to be sealed.”

An unidentified woman at Robaina’s house said Thursday that he has a blood-sugar condition, among other ailments. It is unclear why he was taken to the hospital after he surrendered at the office of his lawyer, Thomas Cobitz, Friday afternoon. Cobitz declined to comment.