Dozens of women protested outside the presidential residence in Mexico City on Tuesday following the murder of a seven-year-old girl - a crime that sparked an uproar in the violence-wracked country.The child's body, which showed signs of torture, was found in the capital on Saturday. Since then there have been protests at her school, at her funeral on Monday and on social media.Dressed in black and many with their faces covered, the protesters demanded an end to impunity and violence against women."Femicide is a state crime," protesters shouted as they demanded that left-wing President Andres Manuel Lopez Obrador take responsiblity to end violence against women."Don't be indifferent, they're openly killing women," protesters also yelled.Later they observed a minute's silence, fists in the air, in memory of the dead seven-year-old.Lopez Obrador has defended authorities' response to this latest murder."We're taking care of the causes" of violence, he said in his morning press conference.Asked by journalists, Lopez Obrador said he wouldn't be against creating a special prosecutor's office to deal with femicide."I think it's a really good idea, as is everything that delivers peace and tranquility," he said.The child had been reported missing on February 11 and her body was found in the southeast of the capital on Saturday.The local prosecutor's office on Monday offered a two million pesos ($107 000) reward for information leading to the identification of her kidnappers and killers.It said the mother had gone to pick up her daughter from school but didn't find her and began a search.Video footage has since emerged appearing to show the girl being held by the hand of another woman and walking in the street on the day she disappeared.Mexico recorded more than 1,000 femicide victims in 2019, according to official figures, although experts believe the true figure may be much higher due to difficulties in registering murders as femicide.