MEXICO CITY (Reuters) - An investigation is underway to find the motive and those responsible for the killing of a Mexican influencer during a live stream, President Claudia Sheinbaum said on Thursday. Authorities say the death of Valeria Marquez, 23, is being investigated under Mexican protocols for femicide, the killing of women or girls for reasons of gender. (Reporting by Raul Cortes; Writing by Drazen Jorgic; Editing by Stefanie Eschenbacher)