MEXICO CITY (AP) — A judge has ordered Mexican authorities to investigate the killings of women in the suburbs of Mexico City, reviving a sensitive issue related to a former governor who is a leading candidate in the presidential race.

Judge Jose Alvarado ruled a national, multi-government agency formed to fight violence against women should reconsider a request by activists to declare a state of alert for central Mexico State, women’s rights activist Maria de la Luz Estrada said Tuesday.

Human rights groups say hundreds of women have been killed or gone missing in recent years in that state, which lies next to Mexico City and is home to 13 million people.

Estrada said her group has documented more than 1,000 killings of women during the six-year administration of former Gov. Enrique Pena Nieto, who is a leading contender in the July 1 presidential election.

State authorities didn’t immediately comment on the ruling, which was issued Feb. 27 but not revealed until Tuesday.

The issue recalled the campaign for justice waged by relatives of women killed in the border city of Ciudad Juarez, where dozens of women were tortured, raped and killed prompting a women’s rights movement that garnered international attention.

“Authorities in Mexico State don’t investigate and instead blame the victims for their own deaths, or in many cases say they committed suicide, without doing a proper investigation,” said Estrada, who coordinates the National Citizens Observers on Women’s Killings.

Political analyst John Ackerman, of the legal research institute at Mexico’s National Autonomous University, said the case could be “another stone in the shoe of Pena Nieto that he’s going to have to deal with” during the campaign.

The judge’s ruling was aimed at the National Agency for Prevention and Eradication of Violence Against Women, which was formed in 2007 from federal, state and local agencies to declare violence alerts and follow up with education, prosecution and prevention programs.

Twenty of 34 agency representatives voted last year against declaring an alert for Mexico State, a move that would have required authorities at all three levels of government to coordinate investigations of gender violence.

The agency can appeal the judge’s ruling.

Pena Nieto and his supporters have said Mexico State’s per-capita homicide rate is no worse than in the country’s other states and suggested the requests for a state of alert were politically motivated. Pena Nieto couldn’t be reached for comment Tuesday.

A study by the United Nations women’s organization found the number of killings of women in Mexico State was in line with the national average and decreased between 2004 and 2009. There were 5.43 women killed per 100,000 in 2004 and 3.66 in 2009, the study said. The national rate increased from 2.46 to 3.4 per 100,000 over the same period, it said.

Estrada denied activists are zeroing in on Mexico State, saying her group has also requested alerts be declared in the states of Oaxaca, Guanajuato and Nuevo Leon.

In Nuevo Leon, a war between two rival drug cartels killed more than 2,000 people last year, including more than 300 women.

In Ciudad Juarez, where 1,200 were killed in drug-related attacks, 196 women were killed in 2011.

“In Mexico State there is a pattern of violence against women, and authorities there are doing everything to deny this is happening instead of working to stop the killings of women,” Estrada said.

A state of alert “would mean they would have to immediately act to protect the life and security of women and to see where the hot spots for violence against women are to prevent the killings,” she added.

Violence against women in the Mexico State drew national attention after a serial rapist and killer escaped from police custody last week.

Police say Cesar Librado, a public bus driver who worked on a route connecting Mexico City with neighboring suburbs in Mexico State, raped eight female passengers and killed seven of them.

He was recaptured Monday after a public outcry calling for the state attorney general to resign.

In filmed testimony, Librado tells investigators he would attack a female passenger when she was the last person riding his bus. He said he raped his victims, choked them to death and dumped their bodies on dark streets.

His first victim survived and went to authorities. Even though she identified Librado and told police what route he worked, he wasn’t arrested until a year and a half later. By that time, he had allegedly raped and killed seven women.

Librado “is a product of the irresponsibility of the governor and the attorney general of the State of Mexico,” said Sergio Mendez, of a human rights group that is part of the petition to declare a state of alert.