Nearly four months after federal agents raided his home and district headquarters, Superintendent Alberto Carvalho announced his resignation as the head of the Los Angeles Unified School District on Sunday.

LAUSD staff said they had received a letter of resignation and would issue a statement later.

In February, the FBI served a series of search warrants at Carvalho's home and the Los Angeles Unified School District's headquarters. Sources told CBS News that the FBI also raided a Florida residence linked to Carvalho. The reason for the warrants is unknown after the FBI confirmed that the underlying affidavit remained under seal.

Law enforcement sources told CBS News that the investigations in both states are directly related to Carvalho. It's not clear what, if any, wrongdoing Carvalho is accused of. The FBI and the U.S. Attorney's Office would not comment on the investigation in February, which is standard until potential charges are filed.   

Prior to joining LAUSD in 2022, Carvalho served as superintendent of Miami-Dade County Public Schools.

A source with direct knowledge of the matter said the investigation predates the Trump administration and is a probe into allegations that Carvalho may have received kickbacks from a business while still superintendent of the Miami school district. The source added that the investigation is not directly tied to the LAUSD or Carvalho's work at the district, and that there is no known culpability or connection to LAUSD. 

More than a week after the search warrants were executed, attorneys representing Carvalho issued a statement denying any wrongdoing and stating that the superintendent "has always acted in the best interests of students and within the bounds of the law."  

"Mr. Carvalho remains confident that the evidence will ultimately demonstrate that he acted appropriately and in the best interests of students," the statement said. "We hope the School Board reinstates him promptly to his position as Superintendent."

Carvalho, who started a four-year, $1.7 million deal earlier this year, has been on paid administrative leave for the last four months.

The LAUSD is the nation's second-largest.