(CNN) Secretary of Defense Mark Esper stated Thursday that he has "an open mind" on whether the Navy should reinstate the fired commanding officer of the coronavirus stricken aircraft carrier, the USS Theodore Roosevelt.

"I directed that investigation a couple weeks ago, it concluded late last week, it is now with the Navy, it will come to me at some point in time. As I am in the chain of command I can't comment on it further, but I've got to keep an open mind with regard to everything," Esper told NBC.

The ship's former commanding officer, Capt. Brett Crozier, was fired earlier this month for what the acting Navy Secretary Thomas Modly, who subsequently resigned, said was poor judgment for too widely disseminating a warning about the spread of virus aboard his vessel, a warning that eventually made its way into the press.

Modly resigned days later over his handling of the incident, actions which included a $240,000 trip to Guam where he slammed Crozier and admonished sailors for giving Crozier a rousing send off in public remarks to the crew.

The number of coronavirus cases aboard the USS Theodore Roosevelt have skyrocketed in recent days, with 655 sailors testing positive as of Thursday, and several have been hospitalized in Guam.

One sailor on the aircraft carrier, who the Navy identified on Thursday, has died from the virus at US Naval Hospital Guam. Chief Petty Officer Charles Robert Thacker Jr., 41, of Fort Smith, Arkansas, was an aviation ordnanceman, according to a statement from the Navy.

The Navy has evacuated more than 4,000 sailors from the ship and moved them into quarantine or isolation on Guam, an evacuation that was urgently called for by Crozier in his letter.

While Modly publicly accused Crozier of sending his letter of warning to 20 to 30 people, the email to which the letter was attached shows that Crozier sent it to 10 people including his direct superior, according to a copy of the email obtained by The Washington Post

"I believe if there is ever a time to ask for help it is now regardless of the impact on my career," Crozier wrote in his email, the contents of which a US official directly familiar with the message confirmed to CNN.

The email was addressed to Rear Adm. Stuart Baker, the commander of the carrier strike group of which the USS Theodore Roosevelt is a component and Crozier's immediate commanding officer.

The email was also addressed to Adm. John Aquilino, the commander of US Pacific Fleet; and Vice Adm. DeWolfe Miller, another senior officer in the Pacific.

The message was also copied to seven Navy captains.

A spokesperson for the Navy declined to comment on the email, citing the ongoing investigation.

Following his ouster Crozier was initially reassigned to the headquarters of the Naval Air Forces Pacific command in San Diego but has remained in Guam where he is completing a mandatory quarantine period.

On Wednesday the New York Times reported that the Navy is looking into whether it can reinstate Crozier, according to Defense Department officials.

'No options off the table'

Esper's unwillingness to rule out reinstating Crozier comes as the Navy has repeatedly said nothing is off the table and that no final decisions made with regard to the investigation.

"As the Chief of Naval Operations has made clear, all options are on the table. That said, Adm. Gilday has received, and is reviewing the Preliminary Inquiry. It will take time for the report to be reviewed and endorsed by Adm. Gilday. No final decisions have been made," Cmdr. Nate Christensen, the spokesman for the Chief of Naval Operations Adm. Mike Gilday told CNN Wednesday night.

The Navy's top admiral told reporters last week that he is "taking no options off the table" as he reviews the investigation.

"I am taking no options off the table as I review that investigation I think that that's my responsibility to approach it in a way with due diligence to make sure it's completely fair and unbiased as I can possibly make it," Gilday told a small group of reporters on a conference call.

Gilday also said that he has not spoken to Crozier and that he is under no pressure in terms of the investigation.

"I'm under no pressure from anybody in terms of my pace or in terms of any kind of influence, nobody has talked to me about that investigation---you're the first people that I'm talking to about the investigation outside of my office," Gilday said.

Asked if the reinstatement of Crozier would signal that his initial ouster was an error, Esper said "Again I can't comment on that we've got to take this one step at a time, let the investigation within the Navy conclude itself if you will as they brief it up we'll take things as we can and make very reasoned opinions and judgments as this progresses."

While much of the attention focuses on whether Crozier will be reinstated to command the ship, the Chief of Naval Operation's investigation set up a deeper look into how top commanders were running the ship when the virus hit the crew.

Gilday ordered a an examination of how healthcare professionals on the ship were communicating their concerns to Crozier and other senior leaders and if that had an impact on the ship's response to the virus outbreak. He also ordered a look at how Crozier and his immediate superior on the ship, Rear Adm.Baker were communicating and why Crozier might have chosen to go around Baker by sending the message to both Baker and admirals much higher in the chain of command.

"That's exactly why we are doing the investigation, to understand the why behind the memo," Gilday said last week.

"I'm speculating in my mind's eye as a former (commanding officer) of a ship years ago, as a (commanding officer) of two destroyers, try to put myself in his shoes and understand why he would have done that and i just don't have the answer to that hence my speculation on there must have been a communications breakdown, or I can envision that somewhere," Gilday added.