Lead homicide detective Mark Biondolino began the investigation into Jocelyn Peters' murder on March 24, 2016. Since then, he has remained connected to the case even though he's now retired from the St. Louis, Missouri, Police Department.  Mark Biondolino : I think you have a responsibility to do that.  Anne-Marie Green : You wanted to see it to the end.  Mark Biondolino : You gotta see it to the end …  Mark Biondolino : … if you're working in homicide … you're not just gonna let it fall by the