A California man killed himself and his 9-year-old son after a custody dispute with the boy’s mother about whether the child should be vaccinated, the San Francisco Chronicle reported. Lesley Hu petitioned for full custody of son Pierce O’Loughlin in July, citing her ex-husband Stephen O’Loughlin’s refusal to let the boy get inoculations. “[O’Loughlin’s] stance on vaccinations has taken on a cult-like tone,” Hu wrote, according to the newspaper. With a trial looming, O’Loughlin agreed on Tuesday to let Pierce get the vaccinations required for school—but on Wednesday he and his son were found shot to death. “I think it is undeniable that Pierce’s father suffered from untreated mental illness, which resulted in his taking the life of his son and his own life,” Hu’s lawyer, Lorie Nachlis, said. “I believe that he did this horrid act in order to exercise the ultimate control over Lesley.”