A trove of emails released under the Freedom of Information Act reveals that Interior Secretary Ryan Zinke regularly uses a private email account to conduct official Interior Department business.

The emails, which were first reported by Politico Pro on Wednesday, show Zinke corresponding dozens of times with his assistant, Caroline Boulton, using two email addresses: his official Interior Department account, which is partially redacted, and a personal account, which is fully redacted. Here they are side-by-side:

Personal address above, official address below

In these emails, Boulton primarily sends Zinke scheduling and briefing materials to his personal address, but it’s clear other Interior staff use it as well.

As he left for a two-week vacation to Greece and Turkey last August, Zinke sent an email to Boulton from his official address asking her to “Please ensure all senior leadership knows my email,” an apparent reference to his personal account, since presumably his senior leaders already knew how to contact him on the department’s official email servers.

In April, Zinke’s then-director of advance, Rusty Roddy, emailed Zinke directly at his personal account — the email is only preserved in these documents because Zinke then forwarded it to Boulton:

That exchange highlights one of the potential problems with Zinke’s personal email use: under federal law, Zinke must forward all work-related email to his official account within 20 days. But there is no way to verify Zinke is complying with the law. It’s entirely a “trust me” situation unless Zinke opens up his personal account to an outside audit.

The second concern is security. Records show Zinke used a Yahoo! address while he was a state legislator in Montana. The redacted personal address in the Interior FOIA documents appears similar to that Yahoo! account. Yahoo!, of course, suffered a catastrophic security breach in 2013, but the full extent of the hack was not made public until last October — all 3 billion accounts were compromised.

If Secretary Zinke was using a Yahoo! account for official business, there would be no way to know whether he was following proper security practices unless he opened up that personal account to a review by Interior IT staff. Given the scope and timing of the Yahoo! breach, it’s possible that Secretary Zinke’s personal account was or still is compromised by hackers. Again, the only way to know for certain is for Secretary Zinke to open that account to a full outside audit.

Finally, the Secretary’s use of private email is breathtakingly hypocritical. At the CPAC conference in 2016, Zinke joked that “I don’t know why we asked the State Department for Hillary’s emails, we should have just asked Putin.”

He made similar comments on Facebook, saying that the Clintons’ “feeling of superiority knows no bounds” after the FBI revealed an additional 15,000 emails in its investigation.

Now it appears Secretary Zinke is following the same pattern he criticized less than two years ago — regularly conducting government business using a personal account. There’s no way to know if he’s following the rules. We’ll just have to take his word for it.

People may wonder why a conservation organization like the Center for Western Priorities cares about how Secretary Zinke emails his staff. The short answer is that this Interior Department is one of the most opaque in history, and the only way anyone can take a peek at the inner workings is through public records requests. The public does not have the right to read Ryan Zinke’s personal emails (and for good reason). But when a high-level government official mixes the two, the American people deserve to know if, when, and how Secretary Zinke uses personal email for official business.