A Honolulu police officer and retired major were arrested by the FBI on Sunday in relation to an ongoing federal corruption investigation into Hawaii law enforcement.

Special Agent Arnold Laanui said Ofc. Minh-Hung “Bobby” Nguyen and former HPD Maj. Gordon Shiraishi were apprehended Sunday, although he wouldn’t share details about the arrests.

Court documents outlining the charges against Nguyen and Shiraishi are expected to be unsealed Monday when they are scheduled to be arraigned in the U.S. District Court of Hawaii.

Cory Lum/Civil Beat

Nguyen and Shiraishi are key figures in an ongoing grand jury investigation that stems from allegations that former Honolulu police chief Louis Kealoha and his wife, deputy city prosecutor Katherine, framed her uncle, Gerard Puana, for the theft of their mailbox in 2013.

Puana’s defense attorney, Alexander Silvert, has contended that the Kealohas wanted to frame his client so that they could gain the upper hand in a legal dispute over money.

Former HPD officer, Niall Silva, has already pleaded guilty to federal conspiracy charges and admitted taking part in the frame job. Silva worked with Nguyen and Shiraishi in HPD’s secretive Criminal Intelligence Unit, which conducts surveillance.

Both Nguyen and Shiraishi received target letters from the U.S. Justice Department indicating they were suspects last year, many months after Silva’s plea deal.

Louis Kealoha also received a DOJ target letter, which ultimately led to his retirement from HPD. In addition to his retirement package, the Honolulu Police Commission approved a $250,000 severance payment that Kealoha is required to pay back if he is convicted of a felony within six years.

Criminal defense attorney Myles Breiner, who represents both Louis and Katherine Kealoha, said the FBI told him that no warrants have been issued for his clients. Breiner said that another alleged suspect, HPD officer Daniel Sellers, also did not receive an arrest warrant.

“The arrests are just another scare tactic to put pressure on various parties involved in the case,” Breiner said.

At this point it’s unclear what Nguyen and Shiraishi’s arrests mean for the ongoing grand jury investigation, which has spanned nearly two years. The current grand jury is slated to expire this month, which has some believing that a wide-ranging criminal indictment is on the way.

Silvert told Civil Beat that he believes the recent arrests should be a signal that the Justice Department is ready to move ahead with indictments, including charges against the Kealohas.

“Mr. Puana is grateful that we’ve now entered a new stage of the proceedings where charges are now being brought against the most culpable people involved,” Silvert said. “We’re going to have to see how this plays out in the next week or two.”

Nguyen and Shiraishi’s attorneys, Randall Hironaka and Lars Isaacson, could not be reached for comment Sunday.

Assistant U.S. Attorney Michael Wheat, who is spearheading the investigation, declined to comment on the arrests of Nguyen and Shiraishi. He also did not want to discuss the ongoing grand jury proceedings.

What’s clear is that Wheat’s grand jury investigation goes well beyond the mailbox case.

Questions have been raised about Katherine Kealoha’s involvement in an alleged ticket fixing situation and what Honolulu Prosecuting Attorney Keith Kaneshiro’s role in that case may be. He has been an outspoken defender of her.

The grand jury also recently investigated the Honolulu Prosecutor’s Safe House, which is an apartment complex for victims of domestic violence, human trafficking and other forms of abuse.

Kaneshiro’s office bought the property with the approval of other city officials from one of his top political donors for $5.5 million shortly after the donor had purchased it for $4.5 million.