BAGHDAD, Iraq -- The sister he has never seen is the one Ali Hussain Mohamed misses the most. He misses his other sister, too, of course, and his mother, taken away with her in the dark of night 21 years ago.

"But the new sister," he explains, "I want to hold her and tell her she is in the arms of her brother. I want her to know we have suffered with her."

Mohamed's mother, Hadiya Saied, was 40 years old when Saddam Hussein's police came to their home in the neighborhood called Dialah and arrested her and his 13-year-old sister, Jinan. The sister he has never seen was born to his mother while she was in prison. Her name is Aliay.

According to government files, the mother was executed in prison and the girls died there, too. But because their bodies have not been found, Mohamed and his family continue to hope.

The missing family members have, in some ways, been part of Iraq's forgotten story. Tens of thousands of Iraqis are searching for their brothers, their sons, their fathers, made to disappear by Hussein's secret police in a reign of terror that has been well-documented and has received renewed attention because of a number of mass graves discovered in the Iraqi desert.

But there is also an unknown but sizable number of people who know firsthand that Hussein's brutality did not discriminate based on gender, and they are looking for their sisters, their daughters, their mothers.

Citizen groups that have recovered government files documenting the executions of Iraqis during Hussein's rule are still sifting through millions of documents trying to provide answers to families searching for their loved ones.

Human rights groups estimate up to 300,000 Iraqis disappeared over the past 23 years, the vast majority of them men and teen-age boys.

But as the extent of Hussein's brutality becomes clearer with each passing day, with each discovery of mass graves, with every tour of his execution chambers, volunteer investigators say that more women than expected are among the dead.

"We have almost 5 million files to go through, so I cannot tell you precisely how many women were killed," says Satlar Jabar, an information manager for the Committee to Free Prisoners, which has been posting the names of the documented dead on walls around Baghdad. "I can say positively that already we have more than dozens and we still have a lot of work to do."

The committee is operating out of a house of a former Hussein body guard, and it is one of the sadder sites in a city filled with misery. For nearly two weeks, volunteers have placed the names of the missing on the walls of the house and on its fence, and swarms of people have scanned them, looking for news on family members that have not been seen for years and even decades.

That is where Mohamed was this week, going through each tattered piece of paper, seeing if he can find the names of his mother and his two sisters.

Their abduction fit a pattern described for years by human rights groups such as Amnesty International and Human Rights Watch.

In many cases, Hussein's police, unable to locate men they wanted for whatever reason, instead took female family members. According to the humanitarian groups, some of the women were raped in front of video cameras and the tapes were sent to family members and others. Some women were imprisoned, tortured and released. Others have never been heard from again.

In the case of Mohamed's family, police were looking for a male cousin, accusing him of being part of the banned Al-Dawa party. When they could not find him -- he had fled to Syria and then to Iran -- the police took his pregnant mother and his sister.

"My sister was a school student," Mohamed says. "How could they imprison a school student?"

He did not know the whereabouts of his mother and sister for six months. He searched the prisons, paid bribes to guards and, finally, located them in a prison in Baghdad's Zafrani district.

"We were so glad they were alive," he says. "We thought, could even Saddam keep a mother and her daughters in prison?"

The answer, as he found out, is that the government did keep such people in prison, and in some cases it executed them. When Mohamed returned to the prison a week later, his mother and sister were gone.

From that point, toward the end of 1982, the family has been searching. In 1995, when Hussein granted amnesty to a limited number of prisoners, the family had as much hope as they had since the arrests.

They were counting on seeing the mother, who would by then have been 53, the 13-year old, who would have been 25, the baby they had never seen, who would have been 13.

With no idea where the women were being held, the family waited to be contacted. The wait stretched on. Two weeks went by without a word.

The family filed a report with the government. Two months later, a member of Hussein's secret police arrived at their house.

"He had certificates for all of their deaths," Mohamed says. "They said, 'Don't try to find their graves, don't talk about them.'" The mother had been executed, according to the paperwork. No cause of death was reported for the girls, only that they were dead.

The family held onto hope. Mohamed says that Hussein's police often falsely reported deaths to try to break families down, to create enough strife within them that they would turn in the person originally sought.

On the walls of the committee, though, he found his mother's name and those of his two sisters. They were buried near Abu Ghraib prison, according to their files, but when he went to the graveyard, there was no record of them there.

"So we still hope," he says. "Maybe there is another file that says they are alive."

If they are, the mother would now be 61; the 13-year-old would be 35; the baby would be 21.