PONTIAC, Mich. — An Oakland County jury has found the mother of the Oxford High School shooter guilty of four counts of involuntary manslaughter, capping an emotional seven-day trial that some legal experts viewed as a litmus test for holding parents criminally responsible for their children’s actions. As the 12-member jury read their verdict on Tuesday afternoon in Oakland County Circuit Court, Jennifer Crumbley, with her hands clasped on a table in front of her, showed little reaction but closed her eyes and looked down. Jurors deliberated for 11 hours before arriving at a decision. Crumbley…