A top Rockville official has resigned in the midst of an investigation into alleged worker discrimination and mistreatment at city hall.

Carlos A. Vargas, the city’s chief human resources officer, left city hall on Friday after resigning earlier this month, city officials said. City mayor Phyllis Marcuccio said she did not know why Vargas had decided to leave, and he could not immediately be reached for comment on Wednesday.

In a series of articles published over the last year, the Montgomery County Sentinel, a local weekly newspaper, reported that several former city employees felt or had colleagues who felt discriminated or mistreated during their time there. Some said evaluations placed in their employee files were altered and did not accurately represent their good work there.

Following the reports, Rockville hired a national law firm, Saul Ewing LLP, to investigate human resources practices at city hall. The Sentinel reports have focused on Vargas, who it reports has lobbied against an outside investigation.

Whether there are widespread human resources problems in Rockville remains to be seen. Saul Ewing, which did not return a request for comment last week, has not completed its investigation.

One former employee, who requested anonymity to speak freely, said she believed she was discriminated against as an older white woman. But other workers said they had no problems with city managers. Kimberly M. O’Sullivan, a former public information specialist, said she believes city managers are among the “hardest working” people she knows.

Louise Atkins, a city council aide, said there have been eight worker grievances filed with the city over the last four years. Two were dismissed, one was withdrawn, and none of them involved alleged discrimination, Atkins said.

Marcuccio said that Vargas’s last day was Friday and that she was notified about the resignation on Saturday. He has taken a job with a nonprofit organization, she said, but she did not know which.

The mayor added that if Saul Ewing’s investigation finds any systemic problems, the city will move quickly to address them. “We have to make sure we get this right,” she said.

When he left, Vargas was making $157,330 a year. City spokeswoman Marylou Berg said Colette Anthony, the city’s labor and employee relations manager, is now serving as acting director of human resources until a replacement for Vargas is found.