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Defense Secretary Mark Esper indicated Thursday that it's possible that Navy Capt. Brett Crozier, who was relieved of his command of the USS Theodore Roosevelt after he raised concerns about a coronavirus outbreak, could be reinstated.

An investigation was completed last week, and the Navy is reviewing its findings, Esper said Thursday on the "TODAY" show.

"It will come to me at some point in time. As I'm in the chain of command, I can't comment on that further, but I've got to keep an open mind with regard to everything," Esper said.

"We've got to take this one step at a time, let the investigation within the Navy conclude itself ... and we'll make very reasoned opinions and judgments as this progresses," he said.

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Crozier lost his command on April 2 after he sent a strongly worded letter to Navy leadership detailing his concerns about the spread of the virus on the aircraft carrier. The letter was leaked to the media, generating national headlines.

One sailor aboard the ship later died of coronavirus-related complications, and Esper said Thursday that 600 or so crew members have been found to be infected.

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Crozier was relieved of his command by Thomas Modly, who resigned as acting Navy secretary in the aftermath of the incident.

Modly at first said Crozier was removed from his post — while remaining in the Navy and keeping his rank — because he sent his letter over "non-secure unclassified email" to a "broad array of people" rather than up the chain of command.

But later, speaking in Guam to the crew of the Roosevelt, Modly said Crozier was guilty of a "betrayal of trust."

"If he didn't think, in my opinion, that this information wasn't going to get out into the public, in this day and information age that we live in, then he was either A, too naive or too stupid to be a commanding officer of a ship like this," Modly said. "The alternative is that he did this on purpose."

Modly first stood by his remarks but later released a new statement apologizing for them.

Modly offered his resignation on April 6, and Esper accepted it, selecting Under Secretary of the Army James McPherson as acting Navy secretary, according to officials.

The Roosevelt has been docked in Guam, a small unincorporated island territory of the U.S. in the Pacific Ocean, since March 27.

The Navy last week said 92 percent of the ship's roughly 4,800 crew members have been tested for COVID-19, with more than 3,600 of them getting back negative results.

"The challenge is it's a crew of 5,000, so this is a small city — a small city where all the residents are cramped into tight quarters — and so you can see how quickly this virus, because of its high transmissibility rate, can move throughout a ship," Esper said. "We're very conscious about not just the TR but other ships on the seas."

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More than 350 of the crew members on the Roosevelt who tested positive were asymptomatic, "so it has revealed a new dynamic of this virus," Esper said. "So we're making sure that we communicate that to our broader force and we take every precaution we can to keep our force healthy and ready."

He said more than 90 other Navy ships at sea have had "no problems."

The outbreak on the Roosevelt "was a special case," Esper said. "We're going to get it behind us."