This April 9, 2014 file photo shows a U.S. soldier walking next to the razor wire-topped fence at the abandoned “Camp X-Ray” detention facility at the U.S. Naval Station in Guantanamo Bay, Cuba. AFP PHOTO/MLADEN ANTONOVMLADEN ANTONOV/AFP/Getty Images

The military prison at Guantanamo Bay, Cuba, may have another problem to deal with: Cancer.

The U.S. Navy acknowledged Monday that it is investigating concerns about possible carcinogens where the Defense Department holds military commissions for detainees. The comments came as Reuters reported that a complaint to the Defense Department Inspector General alleged that at least seven civilians and military members who worked on detainee trials at Guantanamo Bay have been diagnosed with cancer.

The Miami Herald reported Monday that at least three died after falling ill, and that it has found nine individuals who were diagnosed with cancer of the brain, appendix, colon and lymph nodes. Three of them, ranging in age from 35  to 52, have died in the last 13 months, the newspaper added.

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Only one of the individuals, Navy Lt. Cmdr. Bill Kuebler, 44, was identified in the reports. He died July 17 after his cancer “returned with a vengeance” following earlier treatment, according to a report in the Ottawa Citizen. He had served as a defense lawyer at Guantanamo Bay, and represented Omar Khadr, the Canadian citizen who was transferred home in 2012. He was freed on bail earlier this year.

A review by The Washington Post shows that another cancer patient was Army Col. Robert J. Cotell, who died Jan. 6, just before his 53rd birthday. He was a lawyer in the Judge Advocate General (JAG) Corps and remained on active duty right up until his death after doctors diagnosed him with cancer, according to his obituary. He worked at one point for the Office of Military Commissions, which oversees cases at Guantanamo. His family members declined to comment on Tuesday.

A third lawyer, Marine Maj. Joshua Kirk, 36, died June 28, 2014. His cause of death was not listed in his obituary, but Rep. Tim Ryan (D.-Ohio) recognized him on the House floor after his death last summer for his work everywhere from Marine Corps Air Station Miramar in California to the Office of Military Commissions, which deployed him to Guantanamo on occasion. Kirk’s family could not be reached for comment Tuesday.

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The allegations are the latest trouble for the prison at Guantanamo, which President Obama has said repeatedly he wants closed. The Pentagon was racing to move detainees from the facility this spring before lawmakers could block future transfers or halt Obama’s plan to close the prison, defense officials told The Washington Post.

The IG complaint does not allege elevated cancer rates among detainees, according to Reuters. They are currently 116 held at Guantanamo Bay, on a part of the base that is some distance from the area where military commissions are held and where visiting lawyers and others stay. The IG complaint alleged that patients may have been exposed to toxic material where the lived near a location where jet fuel was disposed or asbestos, Reuters reported.

A Pentagon spokesman, Navy Capt. Jeff Davis, told reporters Tuesday that the Navy and Defense Department investigation centers on the military commissions compound at the installation’s old airfield.

“The health and well being of all personnel living and working in Guantanamo Bay is important to us, and we take any health concerns seriously,” Davis said.

Asked if the military is considering screening detainees, Davis said he did not know, but that they would fall in the group of people the Pentagon is concerned about in the investigation. Another Pentagon spokesman, Lt. Col. Tom Crosson, said later in the day that the Defense Department is not currently considering screening military personnel or detainees who have lived on the base, but stressed that the investigation is just getting underway.

Julie Tate and Thomas Gibbons-Neff contributed to this report.

Correction: An earlier version of this piece misspelled the last name of Army Col. Robert J. Cotell and misidentified the member of his family that The Post reached Tuesday. Additionally, this piece has been updated with additional information about the Pentagon’s current stance on cancer screening.