A government watchdog on Monday explained the extraordinary efforts that his investigators made to recover electronic messages sent by FBI employees — and declared he is not confident that there aren’t more that remain hidden in cyberspace.

Michael Horowitz, the Department of Justice (DOJ) inspector general (IG), testified before the Senate Judiciary Committee about his scathing report detailing hostility expressed by several FBI officials toward President Donald Trump at the same time they were investigating his 2016 election opponent, Democrat Hillary Clinton.

Among the most explosive was an exchange on Aug. 8, 2016, between FBI supervisor Peter Strzok (pictured above right) and his girlfriend, bureau lawyer Lisa Page (pictured above left).

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“[Trump’s] not ever going to become president, right? Right?!” Page texted.

Strzok responded, “No. No he’s not. We’ll stop it.”

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Horowitz testified Monday that his office did not receive Strzok’s response until just last month. That is because it was among a large batch of text messages that initially were missing from the records turned over by the FBI.

Horowitz said the “painstaking forensics examinations recovered thousands of text messages that would have been lost or otherwise undisclosed.”

The IG report, released last week, was the product of a 17-month investigation that included reviewing 1.2 million documents and interviewing more than 100 witnesses, some of them on multiple occasions.

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The report found multiple examples of virulent, deep-seated bias against Trump but did not conclude that it impacted the decision not to charge Clinton in connection with her use of a private email server to manage her communications as secretary of state outside of the government system.

Horowtiz testified that the first sign of a problem related to its efforts to review the text messages came when IG investigators discovered they had received no messages from the Strzok and Page cellphones for a four- to six-month period. Both employees voluntarily turned over their government-issued phones, and Horowitz said his office’s cyber team used high-tech digital tools to try to recover the missing messages.

After that, the IG turned to an outside contractor to conduct further work. Then, Horowitz told the committee, the office consulted with the Department of Defense (DOD), which told the IG investigators that it would not have done anything differently.

On the fourth and final step, IG cyberinvestigators discovered that Strzok’s phone had a separate database that collected messages. Forensic investigators extracted the messages from the phone. Horowitz said that is how they found the second part of the August 8 exchange — the Strzok “We’ll stop it” response.

“It’s not clear to us that even outside this blackout period, we’re not convicted that the FBI was collecting — for obvious reasons — 100 percent of the messages.”

That was not until last month, Horowitz said. He added that his office would prepare a second report on those technical issues.

Horowitz said the late discovery has serious implications for the investigation. He said it creates doubt about whether his office managed to recover all of the missing texts from the blackout period.

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“It’s not clear to us that even outside this blackout period, we’re not convicted that the FBI was collecting — for obvious reasons — 100 percent of the messages,” he testified.

The IG report quotes Strzok as telling investigators that he does not remember sending the message. He told investigators that he believes he intended to reassure Page that Trump would not be elected and that he did not mean to suggest that he would use his powers as an FBI officer to impact the investigation.

Strzok insisted that he did not take any steps in either the Clinton probe, or a later counterintelligence operation looking at Russian meddling potentially involving the Trump campaign, to try to influence the outcome of the election, according to the report.

PoliZette senior writer Brendan Kirby can be reached at [email protected]. Follow him on Twitter.