A Democratic Illinois state senator announced his resignation just before the Thanksgiving holiday after being under investigation by the FBI for months.

State Sen. Martin Sandoval sent a letter to the secretary of the Senate explaining he would vacate his office on Jan. 1, 2020, writing, "It is with a heavy heart, I, Martin A. Sandoval, do hereby resign the office of state senator.”

“Respect for my constituents and the Senate convinced me that this action is necessary in order to proceed without distraction to the important work that needs to be accomplished for working families throughout the state of Illinois in the future,” he added.

Sandoval was the focus of a bribery investigation conducted by the FBI. Agents raided Sandoval’s home and his office in Springfield, Illinois, on Sept. 24 in search of information that could connect him to bribery and theft of federal funds.

The senator was investigated as part of a widespread corruption probe that included officials from a construction, transportation and power company, lobbyists, gambling interests, a red-light camera company, and at least three suburban mayors — all from cities in Sandoval’s district. In October, Sandoval stepped down as chairman of the powerful Senate Transportation Committee but refused to leave his seat until his recent announcement.

He has yet to be formally charged with any crimes related to the FBI’s investigation. Several other Illinois officials seem to have been involved in the same raid, including Chicago Ald. Edward Burke, McCook Mayor Jeff Tobolski, and Lyons Mayor Chris Getty.

Sandoval had held his seat for 16 years before his resignation.