. >> forensic examiner maureen botrell discovered that the material was glass.otrell compared it to the glass from the broken window at the crime scene using what's called a refractive index. >> refractive index is a measure of the speed of light through a transparent object. >> the glass is placed in a silicon liquid then heated. the point where the glass disappears is called its refractive index. >> the five fragments that have the same refractive index as the fragments from the door originated from the door. >> they came back with not only the glass fragments that matched the windowpanes but also paint and wood samples contained within that ball bat which matched the doorway or the frame of that door. >> but where did the bat come from? the bosley's children identified it as one of theirs. and it appeared that the glass was broken from inside the house, since most of the glass was outside the door. investigators found something else hidden in the basement. of all places, inside the clothes washer. >> one of the officers found a towel that contained four shell