PONTIAC, Mich. — The mother of the Oxford High School shooter on Tuesday was convicted on four counts of involuntary manslaughter, capping an emotional 11-day trial that some legal experts viewed as a possible precedent setter for holding parents criminally responsible for their children’s actions. As the 12-member jury read its verdict 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 tied to the killin…