Maricopa County Sheriff Joe Arpaio took the stand again Thursday to testify about his role in repeatedly violating a federal judge’s order. While under oath, the sheriff made a surprising admission that the judge’s wife had been the focus of a secret investigation.

The revelation stunned the courtroom. It came out when U.S. District Court Judge Murray Snow directly questioned Arpaio late Thursday morning.

Snow began by asking the sheriff about the contempt of court charges he is facing, including violations of a 2011 order to stop detaining immigrants solely for being in the country illegally.

But then in an unexpected move, the judge brought up a Phoenix New Times article about a possible sheriff’s investigation into Snow himself.

Snow asked Arpaio directly, “Are you aware that I have ever been investigated?”

"You investigated?" Arpaio first responded. "No, no."

When Snow asked if he knew of any investigations into Snow's family members, Arpaio denied his office was involved, but said his lawyers had hired a private investigator.

“We weren’t investigating you, your honor,” Arpaio told Snow. “We were investigating some comments that came to our attention.”

Arpaio revealed he had received an email tip from someone named "Grissom" about an alleged comment Snow’s wife was supposedly overheard making in a restaurant. When asked about the content of that email, Arpaio told Snow, "I think it mentioned that Judge Snow wanted to do everything to make sure I am not elected."

Arpaio claimed that the investigator was able to confirm Snow's wife did make the comment. The judge asked Arpaio on Thursday to save all documentation about the investigation.

One of the many questions raised by Arpaio's revelation is which attorney was involved in hiring the private investigator. When Snow asked in court, Arpaio said, “I believe it would have been Casey,” a reference to his former attorney, Tim Casey.

Casey’s attorney, Karen Clark, said in a statement that Casey’s continuing ethical obligations to Arpaio and MCSO mean he has only a limited ability to respond to the statements made Thursday in court. 

“Mr. Casey is confident that when the evidence the Court’s monitor is gathering is reviewed, it will reveal that Mr. Casey was never involved in an investigation of Judge Snow or his family,” Clark wrote.

Arpaio also testified that with the help of an MCSO Sheriff's Posse member named Mike Zullo, who was also behind the sheriff’s investigation of President Barack Obama’s birth certificate, he had hired a confidential informant in Washington state to investigate a second issue that may have involved Snow. 

Arpaio described it as an investigation into “computer tampering” and "bank fraud." His testimony suggested he was investigating whether the U.S. Department of Justice was intercepting communication from various judges, a law firm the sheriff uses, and the sheriff himself. Arpaio admitted the investigation hadn't yielded anything and was wrapping up.

When asked to describe why Arpaio had hired the confidential informant, he told Snow that he, "seemed to indicate that someone was penetrating in the e-mails of our local attorneys and others, judges, that type of thing, which we can't prove."

Snow asked, "And was I one of those judges?"

"I think you were one of the judges," Arpaio responded.

"And were you concerned then that that might be affecting my judgment or neutrality in this lawsuit?" Snow asked.

Arpaio said no. 

Many in the courtroom were stunned by the admissions.

“It’s disturbing, to say the least,” said Dan Pochoda of the ACLU of Arizona. He represents the plaintiffs in the racial profiling suit against the sheriff. “It is concerning. It certainly doesn’t reflect well upon this agency.”

Arpaio has a history of investigating his political enemies and rivals.

Former U.S. Attorney Paul Charlton told The Associated Press there should be a probe to find out if the investigation of Snow’s wife was lawful. There are federal statutes that criminalize the intimidation of federal officials.

But Arpaio’s criminal attorney, Mel McDonald, denied that was the scenario with his client.

“There are statutes all over the place that deal with issues such as intimidation,” said McDonald, who is also a former U.S. Attorney. “It isn’t here, and that is what you will hear tomorrow.”

Later speaking in front of a large group of reporters, McDonald added, “There’s been no evidence the sheriff ordered the judge’s wife to be investigated.”

McDonald said more information would come to light Friday, when MCSO Chief Deputy Jerry Sheridan is scheduled to testify.

Earlier Thursday morning, the plaintiffs used Arpaio’s own media appearances and press releases in an attempt to show the sheriff’s violation of Snow's 2011 order was willful. Arpaio was heard defiantly pledging to continue enforcing immigration laws.

The court heard a clip of Arpaio six months after the order describing to Fox News his immigration policies. “If there is a state criminal crime, if they are illegal they are going to jail,” he said. As for the others, “We are going to call ICE to take them off. They have been taking these illegal immigrants off our hands when we have no state charges against them.”

But detaining those immigrants to turn them over to Immigration and Customs Enforcement is barred by the 2011 order.

Arpaio insisted to the plaintiffs’ attorney questioning him that his violations of the judge’s orders were not on purpose.

At one point Arpaio turned in his seat and offered Snow an apology.

“I have been a federal official for 22 years. I have deep respect for federal courts and federal judges,” Arpaio said. “I didn’t know all the facts of this court order and it really hurts me that after 55 years ... to be in this position. So I want to apologize to the judge. I should have known more of his court orders. It slipped through the cracks.”

Updated April 24, 11:45 a.m.