(NewsNation) — New Yorkers are left with more questions than answers as federal officials probe members of Mayor Eric Adams’ administration and top city officials resign.

Most recently, New York City Health Commissioner Dr. Ashwin Vasan publicly announced he would resign early next year. Vasan was appointed in December 2021 while the Omicron variant of COVID-19 was in full swing and was soon after confronted with the city’s first case of Polio in a decade. He’s the third high-ranking city official to announce a resignation this month.

Former New York City Police Department Commissioner Edward Caban and chief legal counsel Liza Zornberg both announced their resignations in recent weeks.

Unnamed sources reportedly told NBC New York that Vasan’s announcement is unrelated to the investigation involving several other city officials.

“As anyone with a family — or a chosen family — knows, you are never alone in service,” Vasan wrote in an official statement he posted to X. “My wife and three young children have served alongside me, bearing the brunt of my absence and shouldering so much…While this was a hard decision, it was the right one for me and my family.”

What is the FBI investigating?

It’s unclear. Federal prosecutors have declined to comment on the investigations or provide details about their scope. People familiar with the situation have described multiple, separate inquiries involving senior Adams aides, their relatives, campaign fundraising and possible influence peddling at the police and fire departments, the AP reported.

Some of the individual investigations so far have touched on allegations of fire officials favoring donors and expediting their inspections, bribery within the city’s building department and straw donations.

Questions have also probed Adams’ team’s involvement Turkish entities and their possible contributions to the mayoral campaign. 

Federal investigators have visited more than a dozen members of Adams’ administration in recent weeks. Throughout the investigation, officials have taken devices from the police commissioner, the head of the public schools and other confidantes both in and out of City Hall.

Adams has not been accused of wrongdoing and denies any knowledge of criminal activity.

Who has retired?

Caban, the city’s former police commissioner, resigned in early September — one week after investigators seized his phone.

Federal officials seized phones from Caban and two New York police lieutenants who worked in the commissioner’s office and on his detail, sources told Nexstar’s WPIX. Officials also took devices from the home of Caban’s twin brother, James Caban — a former police officer who now runs a nightlife consulting business, according to the AP.

Adams’ top legal adviser Lisa Zornberg also resigned abruptly around that time. Zornberg is a former federal prosecutor in the U.S. attorney’s office and leads some of the investigative efforts into the Adams administration. Officials did not seize her phone, the AP reported.

The Associated Press contributed to this report.