By Lisandra Paraguassu and Adriano Machado BRASILIA (Reuters) – Brazilian President Luiz Inacio Lula da Silva said on Thursday that security force members were complicit in letting an anti-government mob ransack the seat of power in Brasilia, and promised to weed out hardcore supporters of his predecessor. The task of screening out those actors will be complex, his senior aides said, but investigations have begun to see who was responsible for letting backers of former President Jair Bolsonaro storm and vandalize the presidential palace. “There were a lot of people who were complicit in this a…