they found paint on both the t-shirt and the bathrobe with the same chemical makeup. >> what i believe happened now, there is an evidence transfer from the blue t-shirt deposited on to the pink bathrobe. >> this proved that sarah had worn the robe over the top of her t-shirt. finally, investigators analyzed the gloves found in the garbage. >> when you handle an item and you leave behind the oils and residues from your skin, that contains skin cells, and we are oftentimes able to get dna from those samples. >> scientists swabbed the inside of the gloves and found dna from only one person. >> sarah was the source of the dna found on the latex glove. >> all the clothing found in the garbage can was then checked for gunshot residue, a gas created by gunfire that can adhere to the shooter. >> we sent the robe, we sent the leather glove and we sent the latex glove to a lab in chicago, akrone and associates. they eventually found gun residue on all three items. >> but investigators had one final question. why wasn't sarah's hair covered in blood when she went to her neighbor's house to report the murders? did she wear some kind of hat? if so, where was it? investigators learned that sarah johnson disagreed vehemently with her parents over her relationship with her 19-year-old boyfriend, bruno santos. instead, prosecutors say sa turned to violence. in october of 2003, sarah johnson was charged as an adult. >> sarah, i have a warrant for your arrest for the murder of your parents, diane and alan johnson. you're charged with two counts of murder and you're under arrest. >> it was a sad moment, because it's a 16-year-old that did this. it's sad for everybody involved. >> the trial of a teenaged girl killing her parents was a national sensation. >> there were three people in the johnson house that morning when alan and diane were murdered. two of them did not come out.