The Texas secretary of state’s office on Friday called into question the citizenship status of 95,000 registered voters who were found to have identified themselves at some point to a state law enforcement agency as noncitizen, legal residents of the United States.

The office of David Whitley, the secretary of state, said its findings were a result of an 11-month investigation with the Texas Department of Public Safety that also found that about 58,000 people on the list had voted since 1996. The results of the investigation were referred on Friday to Attorney General Ken Paxton, who said he planned to open a potentially sprawling investigation.

The two announcements seemed certain to reignite partisan debates over the frequency and impact of voter fraud, which Republicans have claimed is rampant in America. Democrats scoff at that notion, and a voter fraud commission started by (and later angrily disbanded by) President Trump found no evidence of widespread electoral fraud.

“Every single instance of illegal voting threatens democracy in our state and deprives individual Texans of their voice,” Mr. Paxton, a firebrand conservative who has prosecuted isolated cases of illegal voting with gusto, said in a statement. “Nothing is more vital to preserving our Constitution than the integrity of our voting process, and my office will do everything within its abilities to solidify trust in every election in the state of Texas.”