New York ? The U.S. Army says it has reopened an investigation into the suspected bludgeoning death of a key Iraqi government scientist in American custody, a chemist who allegedly experimented with poisons on prisoners in the days of Saddam Hussein.

Mohammad Munim al-Izmerly, 65, is the only known weapons scientist among at least 96 detainees who have died in U.S. custody in Iraq. Questions have surrounded the death since his body was dropped off at a Baghdad hospital in February 2004, two weeks after he died.

When the chemist’s death first came to light in news reports last May, the U.S. military, newly under fire for prisoner abuse in Iraq, refused to answer queries about it. Now, months later, the Army says an investigation has begun.

“The case was initially closed, but after further investigative review a determination was made to reopen the investigation,” Army spokesman Christopher Grey said.

The Pentagon would say nothing about the timetable or thrust of the inquiry. But Rod Barton, an Australian member of the CIA-led teams that questioned al-Izmerly and other weapons scientists, said such prisoners might have been beaten during the futile U.S. hunt for banned arms in Iraq.

When al-Izmerly’s body was delivered to Al-Kharkh Hospital, the Americans enclosed a death certificate saying he died of “brainstem compression,” without saying what caused it, Britain’s Guardian newspaper reported after viewing the document last year. A subsequent Iraqi autopsy determined he was killed by a blunt trauma injury — a blow to the head — Iraqi doctors told Baghdad reporters.

In contrast to a “distinguished chemistry professor” — the portrayal in one news report last May — U.S. weapons investigators now say al-Izmerly was an early leader of Iraq’s effort to make chemical arms, and an assassination specialist who once devised a “poison pen.”

The Egyptian-born scientist had been in U.S. detention since April 2003. His family was allowed to visit him in January 2004 at the Baghdad airport, where he was believed held at Camp Cropper, a U.S. military detention center for “high-value detainees.”