A 16-year-old from Utah is being charged as an adult with the murders of his mother and three siblings and the attempted murder of his father. A motive for the family massacre is still unclear, but court documents describe a cold-blooded quadruple slaying. Authorities say Colin Haynie of Grantsville first shot his mother and 12-year-old sister as they returned home from school, then lay in wait for younger siblings Matthew and Alexis and killed them, too. The documents say that when Colin’s father came home an hour later, he shot him in the leg; the dad then wrestled the gun away.