The chief of staff to former Mayor Kirk Caldwell testified as a witness before a federal grand jury Thursday, a month after receiving a subpoena as part of an ongoing public corruption investigation by the U.S. Department of Justice.

Gary Kurokawa, a former deputy director of the city Department of Budget and Fiscal Services and former administrator of the city’s Real Property Assessment Division, let Caldwell know about the testimony after it concluded Thursday, Caldwell campaign spokesperson Glenna Wong told the Honolulu Star-Advertiser.

Caldwell’s former managing director, Roy Amemiya, former Honolulu Corporation Counsel Donna Leong and former Honolulu Police Commission Chair Max Sword are accused of conspiring to defraud the government by setting up a payment to former Honolulu police Chief Louis Kealoha for $250,000 to voluntarily leave the Honolulu Police Department in January 2017.

Caldwell pulled out of the Governor’s race the day before Kurokawa testified, saying in a statement Wednesday that a “lack of funding” and “lack of momentum” were reasons for dropping out.

“Gary Kurokawa did advise Kirk Caldwell that he had been subpoenaed over a month ago, and did let Kirk know again after he testified,” Wong said in a statement. “The investigations do not have anything to do with Kirk Caldwell withdrawing from the race.”

Caldwell has said he does not believe his former cabinet members did anything wrong. In February, he issued a statement saying he has “great confidence in the integrity of Ms. Leong, Mr. Amemiya and Mr. Sword.”

Amemiya, Leong and Sword turned themselves in to the FBI on Jan. 12 and entered pleas of not guilty.

“Kirk Caldwell has not received a target letter, subject letter, nor any correspondence from the U.S. Department of Justice, nor has the USDOJ requested to interview him,” said Wong.

The trial for Amemiya, Sword and Leong is set for June 13.