A 56-year-old prisoner in U.S. military custody in Baghdad died Saturday, the military said Monday in a brief statement.

The man, whose identity was not released, died at 11:23 a.m. “as a result of complications from an apparent stroke,” the statement read.

“The detainee was admitted to Task Force 344th MED, at Abu Ghraib, Dec. 30 and was being treated for an irregular heartbeat,” the military said. “An attending physician pronounced him dead [Jan. 7] after he failed to respond to aggressive medical treatment.”

The Army’s Criminal Investigation Command, known as CID, is looking into the incident. Monday’s statement said that such an investigation is standard procedure after any detainee death.

An autopsy will be performed on the man before his remains are released to his family, military officials said. That process is also standard procedure after a detainee death in the custody of Multi-National Force Iraq, officials said.

It is the second prisoner death in the past week. An “unidentified male Iraqi detainee” died while being transferred from Ar Rutbah to Camp Korean Village on Jan. 4, the U.S. Marines said last week. The man was one of 23 people detained and being taken by convoy to a U.S. base.

When the convoy arrived at the detention facility, Marines found the man nonresponsive. Medical personnel were called to the scene and rendered aid, but the man did not regain consciousness and was pronounced dead shortly after.

An investigation into that incident is ongoing, officials said.

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