BAGHDAD -- A Baghdad mental hospital administrator has been arrested on suspicion of supplying mental patients to insurgents for use in suicide bombings, a U.S. military spokesman said yesterday.

The interim administrator at al-Rashad psychiatric hospital was arrested Sunday and is being questioned in U.S. custody, said the spokesman, Rear Adm. Greg Smith.

The arrest was part of the probe into double suicide bombings Feb. 1 in Baghdad, which claimed at least 99 lives and was the worst such attack in the capital in nine months.

Iraqi authorities announced within hours of the blasts that the perpetrators were teenage girls with Down syndrome who might have been unwilling participants. U.S. authorities now think that version of events was inaccurate.

A senior U.S. official who asked not to be named because he wasn't authorized to discuss the case publicly said U.S. investigators now thought that the bombers were adults - one in her 20s, the other in her 30s - with long histories of psychiatric conditions, including depression and schizophrenia.

Investigators think that early Iraqi accounts that the bombers escaped security efforts because they were well-known in the two markets where the bombings occurred also were incorrect. While one of the women was from Baghdad, the other was from outside the city, the senior U.S. official said.

The administrator who's being questioned is suspected of using his access to mental-patient records and possibly providing them to Islamic extremists, the official said.

The U.S. version of events squares better with what witnesses at the market have told reporters.

Vendors and other regulars interviewed at the Al-Ghazil and New Baghdad markets said they hadn't recognized either woman, and vendors at the New Baghdad market said the bomber there had shown no signs of obvious mental impairment or Down syndrome.

The witnesses also said that Iraqi police investigators had yet to return to the markets to question them about what they'd seen or to learn more about the women.

Security remains an issue at the markets: Women entering them still aren't patted down for explosives or other weapons.

Mohammed Sahib, 23, said he remembered the bomber at the New Baghdad market because she was the first woman he'd ever seen there.

He recalled her exiting a gray Opel sedan. She wore a light veil over her face and a black cloak, known as an abaya. Sahib described her as "beautiful" and said she was in her late 20s or 30s.

"Anyone who says she has Down syndrome is a liar," he said.

He said he'd asked where she was headed. "I want to buy some seed," he said she replied.

She walked away calmly through the crowd. Then, he said, he felt the explosion.