it all began on an ordinary day with the otero family. this is part one of btk bind, torture, kill. >> i came through the back door, cut the phone lines, waited at the back door, had reservations about even going in or just walking away. but pretty soon the door opened and i was in. >> the otero family was a family of seven headed by father joseph and his wife julie. they had both been born in puerto rico, but they moved to new york as children and there they met in high school. >> my family was your typical military family. my father was an air force sergeant, and my mom was a stay at home mother. good catholic woman. >> they had five children ranging in age from 15 all the way down to nine. >> we were all into school. my father expected us to get good grades and we stayed pretty athletic and into sports. >> hard workers, good parents, kids doing well in school. really not a care in the world we came to wichita, kansas in the 70s because my father had retired overseas and was looking for work. >> he worked on jet engines and that was the

great little town to be from the morning of january 15th, 1974 was just a regular school day in the otero household until the unthinkable happens. >> an intruder enters their home and commits atrocities against this innocent family. >> i saw my parents bodies. it just felt like somebody had ripped my chest wide open and pulled my heart out and investigators are trying to piece together the evidence and find the killer. >> when in april, another brutal killing when the crime scene investigators found the dna stain on the female clothing, they collected it. >> but there was no dna testing at that time. and so they packaged it properly, sealed it up, and put it with the rest of the evidence. >> in wichita instantly changed. it wasn't an innocent city anymore. >> killer breaks in. he's he's lying in wait, and he's thinking he will be able to subdue her and do whatever he wants and fill his fantasy. >> btk studied a lot about police techniques. he knew that the police basically were looking for a common m.o. >> the btk nomenclature bind torture, kill. and that's how he wanted to be known so he