A prominent Mexican activist who investigated her daughter’s cartel death has been shot and killed—on Mexico’s Mother’s Day. Miriam Rodriguez, who died on the way to the hospital Wednesday, was shot in her home in the northern state of Tamaulipas. She spent her life searching for “disappeared” victims in the violent area, and she was most famous for uncovering the kidnap and murder of her own daughter by the Zetas drug cartel. Mexico’s national human-rights commission spoke out in the aftermath of her death, blaming the Mexican government’s failure to protect its citizens, including human-rights advocates. Rodriguez’s daughter went missing in 2014, after which she began a comprehensive search. She found her daughter’s remains in a hidden grave in a small town. Eventually, she provided police with enough information to jail the responsible gang members—until one of them escaped in March and she began receiving threats. Rodriguez asked for police protection, but she received none, colleagues said. Tamaulipas Attorney General Irving Barrios said he had provided three police patrols to her home every day.