judy melinek: his center of gravity was too low. razor scooter, his center of gravity is too low to go over that banister. josh mankiewicz: it all pointed to a chilling alternate scenario. according to dr. melinek, someone assaulted max, and then he somehow went over the banister. in other words, this was a homicide. i would much rather have them to say, you know what? this was an accident, and here's why. no mom wants to hear that her son was a victim of a homicide. josh mankiewicz: and if someone killed max, dr. melinek's theory focused on one person. i think rebecca was somehow involved. but how much she was involved, and to what degree, she took that to the grave. josh mankiewicz: that alarming suspicion was only the beginning. because it wasn't just dina who was investigating. rebecca's sister, mary, was equally convinced rebecca would never hurt max or kill herself out of guilt. two women coping with terrible tragedies, neither willing to accept the sheriff's department's conclusions. mary was about to make some incredible acc