San Francisco City administrator Naomi Kelly is the unnamed “senior official” who alerted federal agents this week that Public Works Director Mohammed Nuru had disclosed details to her of the FBI’s ongoing corruption probe, according to sources with knowledge of the matter.

It was Kelly’s action, NBC Bay Area’s Investigative unit has learned, that led FBI investigators to confront Nuru a week after he had been freed in exchange for his undisclosed cooperation in the evolving corruption case.

When he was released on Jan. 21, federal court documents show, Nuru had already admitted to wrongdoing as part of a deal with prosecutors.

“During meetings with the government on and before Jan. 27,” the complaint indicates, “Nuru admitted that he accepted gifts and other items of value in exchange for official acts” as director of Public Works. Under the deal, he promised not to disclose the probe to anyone.

After Kelly – who is reportedly a personal friend of Nuru -- contacted the FBI, Nuru was questioned again, court documents show. While he initially maintained he had kept silent, authorities say Nuru ultimately “confessed that he had lied and admitted that, on multiple occasions the prior week, he had discussed the investigation and his cooperation with the government with the senior city official. He also identified several other witnesses in the investigation with whom he had discussed the charges against him and/or the investigation.”

While the complaint mentions Nuru having received a tractor, a $2,000 bottle wine and other gifts in exchange for favors, he is not formally charged with taking bribes. Instead, along with lying, he is alleged to have set up a $5,000 bribe that was allegedly offered by the owner of Lefty O’Doul’s restaurant, Nick Bovis, to a city airport commissioner. Authorities say Nuru was at the meeting back in 2018 when Bovis allegedly handed an envelope with cash to the commissioner in exchange for her help securing a lease for a chicken restaurant at the airport.

Court records indicate the veteran SFO commissioner, Linda Crayton, refused the money. Agents say she is overheard on an informant’s tape of the meeting saying she would help anyway because her friend Nuru had asked her. Crayton resigned from her post Wednesday, citing health reasons. Her attorney says she is innocent and willing to cooperate in the probe.

In the end, Bovis never got the lease. His attorney has not commented on the allegations that could lead to a 20 year prison term.

Nuru, meanwhile, faces up to 25 years in prison. His attorney, Ismail Ramsey, issued a statement calling his client, a father of five, “a dedicated public servant in San Francisco for decades.”

“He is grateful to have worked alongside the many committed and talented individuals of Public Works.” Ramsey said. “Mr. Nuru welcomes and looks forward to addressing these charges in court."