ST. LOUIS — A pathologist who failed to pinpoint why a former Illinois prosecutor’s first wife died in 2006 has had her work discredited in other death investigations, including one involving a 2-year-old boy, according to authorities and records from the cases. Jessica Bowman’s ruling of the cause of Cory Lovelace’s death as inconclusive left the case open until ex-prosecutor Curtis Lovelace was charged last month with killing her. Authorities said Bowman missed what they now consider …