After an incident of police brutality on the streets of Las Venturas, grandma decided to take revenge. She saw how violent the cops can be and resented them. This cruelty made Babushka finally stand out... Thus, the SAPD elimination began.
https://www.youtube.com/watch?v=EVLjcTvp4Eo
Part 2:
https://youtu.be/fCUz-MtyXfA
