MEXICO CITY - A mother campaigning to bring the confessed killer of her 16-year-old daughter to justice was herself gunned down in view of a closed-circuit television camera, leaving images that shocked Mexicans over the impunity of the killers.

The killing of Marisela Escobedo unfolded Thursday night on the sidewalk in front of the governor's palace in the capital of Chihuahua state.

Escobedo, 52, a retired nurse, was at a protest booth in the main plaza across the street demanding that the man who confessed to killing and dismembering her daughter, Rubi Marisol Frayre, in 2008 be hunted down.

A closed-circuit camera captured the 20 seconds or so at 8:10 p.m. when a man got out of a white Volkswagen Jetta and approached Escobedo. Frightened by him, she ran across the street, dodging traffic, the assailant only footsteps behind her. He shot her in the head with a 9mm pistol at the entrance to the palace.

The video shows the killer running back across the street and getting in the waiting car, which pulled away.

The brazen hit of a grieving mother - in the capital of a state renowned for hundreds of slayings of women and girls - sparked condemnation from within Mexico and from abroad.

"The death of Marisela adds to the long list of women murdered in Chihuahua," Norma Ledezma, head of Justice for Our Daughters, said through sobs in a telephone interview moments before a Friday march through Chihuahua City.

The human-rights group Amnesty International called Escobedo a "tireless fighter for justice for her daughter" who had become emblematic of women fruitlessly seeking justice for murders in Chihuahua state, which borders Texas and New Mexico.

"Once again, the negligence of federal and state authorities to prevent and punish violence against women in Chihuahua has left relatives and human rights organizations to suffer reprisals for their efforts for truth and justice," the group said.

After Escobedo's daughter disappeared in August 2008, her live-in boyfriend, Sergio Rafael Barraza, fled the state. Nearly a year later, the mother located him in nearby Zacatecas state. Barraza later confessed and identified the site where he had buried the girl after killing her.

This past April, a three-judge panel acquitted Barraza of the murder despite his confession, freeing him. After complaints from then-Gov. Jose Reyes Baeza, an appeals court overturned the verdict and instated a 50-year prison term.

Prosecutors made little effort to find the fugitive, leaving Escobedo to track him down once again. She did so, leading a law enforcement unit in July to Zacatecas state. But Barraza escaped again.

Gov. Cesar Duarte, who succeeded Reyes Baeza, said he was "absolutely sure" that Barraza was behind Thursday's killing of Escobedo.