A federal special prosecutor reviewing hundreds of murders of women in Ciudad Juarez over the past decade said Thursday that investigations into the crimes had been hampered by "grave deficiencies" on the part of local police.

The special prosecutor, Maria Lopez Urbina, said that after reviewing files in 50 of the cases, she had recommended that the Chihuahua state attorney general investigate 81 current and past Ciudad Juarez police officials for possible negligence.

More than 300 women have been murdered in Ciudad Juarez since the early 1990s, and human rights activists say that about 100 of them were raped and murdered in what appear to be serial killings. Rights groups around the world have protested the government's inability to solve the murders, and activists say that Ciudad Juarez has become a symbol, raising doubts about President Vicente Fox's commitment to improving Mexico's record on human rights.

"To the parents, brothers and sisters, children or husbands of these women who were unjustly deprived of their lives, we promise our best effort to make the expression 'not one more death' a reality," Fox said Thursday, accepting Urbina's report at the presidential offices in Mexico City.

Eric Olson of Amnesty International in Washington called Urbina's report "a good start" because it recognized incompetence and negligence by local police officers that Fox, his attorney general and other top federal officials had previously not acknowledged.

But Olson said that having the state attorney general review allegations against the local police was "like having the fox guard the henhouse."

"The state attorney general's office is complicit in this problem," said Olson, citing an Amnesty International investigation that concluded officials at the local and state levels had botched investigations and falsified evidence that led to scapegoat convictions of several people.

"All the cases of people in jail should be reviewed," Olson said.

Urbina, who was appointed in January, said that of the 50 cases she has reviewed in her first four months, most were likely caused by domestic or random violence. Laurie Freeman of the Washington Office on Latin America, a human rights and policy group, called that finding "inconclusive."

"The problem in Juarez is more than whether or not a serial killer is on the loose," Freeman said. "It's the prevailing attitude that violence against women is acceptable. That attitude is what has led to hundreds of unsolved murders of women in the past decade."