barely visible droplets of blood on the lowerhand of his t-shirt. blow back. this is what happens when you shoot somebody at close range. you get that blood on your shirt. >> correct. if you got high-velocity impact spatter on his t-shirt, he has to be within four feet of the child at the time that the child was killed. >> reporter: the prosecution believed david camm shot from inside the car. targeting jill in the back seat. that's how her blood sprayed on his shirt. but why? why would david camm kill his family? the reason for those killings, the prosecutor declared, was that david camm was a philandering husband. >> that's probably one of the first times i ever heard kim cry. >> remember kim's old friend marcy? the prosecutor had her testify about an affair david had when kim was pregnant in late 1994. marcy told the court kim called