for marilyn's family and for the family of renee farnsworth. >> renee is as much a victim as anybodyher friend. >> she was in the wrong place at the wrong time. >> reporter: investigators compiled the preliminary evidence from eyewitness accounts. >> we know as soon as they got out of the car they are attacked, accosted by a lone gunman, six feet to 6'2", slender, well-built, something covering his face, probably a hoodie. >> reporter: it looked like a targeted killing. >> there's no other motive. there's no burglary, there's no sexual assault, there's no car theft, there's nothing. >> reporter: but there was potentially valuable physical evidence. >> the bullet casings from the scene were a -- nine millimeter. and when you combined the bullet casings with the bullets from the victims it was consistent with a ruger nine millimeter p85, semi-automatic handgun. >> reporter: hanging over everything was the question, who would have wanted marilyn dead? detectives knew from the moment linda disappeared. marilyn had accused linda's ex-boyfriend, jr, of harming linda it became a nasty feud.

. >> reporter: renee farnsworth, the second victim, marilyn's friend and neighbor who had gone with her renee's daughter, dorothy, pleaded to the public for help. >> i'm here for my mom. i hope that somebody out there has it in their heart to come forward and help us with this. >> reporter: someone had ambushed the two women in the driveway. renee had been shot once. marilyn twice. the second shot at close range to the head. >> reporter: do you have crimes like that in tucson in that neighborhood? >> i'm a homicide detective. i wouldn't need this job if we didn't have any homicides. and how nice would that be? but this is incredibly rare to have a random act of violence to two women who have done nothing to anybody. >> reporter: how quickly, detective, do you start to connect the dots and say, "this is the mother in the same house of the missing linda watson?" >> immediately. immediately. >> reporter: several hours later, pima county sheriff's investigators went to the last place the two women had visited. >> two detectives came over and had told us they were there to do a well check on