Retired police officer Niall Silva admitted repeatedly lying to the FBI, federal prosecutors, grand jurors and in court testimony in connection with the alleged theft of the mailbox of retired Honolulu Police Chief Louis Kealoha and his wife, former city deputy prosecutor Katherine Kealoha.

But on Tuesday he told jurors he was telling the truth.

Appearing as a government witness on the fourth day of the federal conspiracy trial against the Kea­lohas and three former and current police officers, Silva said he conspired with two of them — Lt. Derek Wayne Hahn and officer Minh-Hung “Bobby” Nguyen — to provide false information in the case.

The defendants, including retired Maj. Gordon Shira­ishi, are accused of trying to frame Katherine Kealoha’s uncle, Gerard Puana, for the 2013 mailbox theft from the couple’s Kahala home and lying to investigators about what they did.

Asked Tuesday why jurors should believe Silva was telling the truth after a year and a half of doing just the opposite, the retired officer, who reached a plea deal with the government in 2016 before the defendants were indicted, said, “Because I took the oath today, and I would surely not put myself and my family in jeopardy again.”

Silva was the first of two Honolulu Police Department officers who reached plea agreements in the case to testify for the prosecution.

Silva spent most of the afternoon on the witness stand, providing a steady dose of dramatic testimony after a morning court session marked by a couple of experts addressing how to properly assemble a certain type of mailbox and what its retail value was and the visible difference between a Lexus and an Acura vehicle.

That information is important to the prosecution’s case and to help understand the grainy surveillance video showing the alleged thief pulling up in front of the Kealoha home in a white car and plucking the mailbox from its post.

When Silva saw Puana in December 2014 for the first time at the federal criminal trial for the mailbox theft, Silva said his “heart sank” and he became upset because Puana, a bodybuilder, wasn’t the scrawny man in the surveillance video and didn’t even drive a white car.

“I perpetuated a lie, and it was against someone who wasn’t guilty,” he testified.

Before the mailbox theft, Gerard Puana and his mother, Florence Puana, who is Katherine Kealoha’s grandmother, had sued Kea­loha over a family financial dispute. Prosecutors say the defendants attempted to frame Gerard Puana to discredit him in the civil case.

Silva, a technician for the secretive Criminal Intelligence Unit whose members are picked by the chief, said a report he filed about retrieving the video evidence from the Kealohas’ home contained multiple false statements. He said he repeatedly lied to investigators and others in order to keep his story consistent.

“If I was to change that, it would put me in jeopardy,” he said.

Several attorneys for the defendants cited Silva’s history of lying to try to undermine his credibility in the eyes of the jurors.

They said he only changed his story once the feds caught him in a lie and because he was hoping to benefit from the plea deal.

Randall Hironaka, attorney for Nguyen, questioned whether Silva expects to benefit from his cooperation when prosecutors make a recommendation at his sentencing.

Silva, whose HPD career spanned from 1989 to 2013, faces a maximum sentence of five years in prison and a fine of up to $250,000.

He said he doesn’t expect anything from his cooperation, though he acknowledged that he hopes to benefit.

Asked why he would cooperate if he doesn’t expect a benefit, Silva said he simply wanted to tell the truth.

“I wanted to come clean and not have to lie anymore,” he said.