(Reuters) -A Michigan judge held a preliminary hearing on Tuesday to decide whether prosecutors had enough evidence to bring involuntary manslaughter charges against the parents of a teenager accused of killing four high school students. James and Jennifer Crumbley, are accused of buying the weapon as a Christmas present for their 15-year-old son Ethan, and ignoring warning signs as late as the day of the Nov. 30 shooting in Oxford, Michigan. The shooter, Ethan Crumbley, has already been charged with first-degree murder in the deadliest U.S. school shooting of 2021. All three have pleaded not …