testified her dog picked up laci's scent at the berkeley marina. and, said the prosecutors, it was obvious scott peterson knew laci and conner were gone for good. he had even turned conner's nursery into a storage room. >> put office furniture and pillows and a locking device from a car in there. scott wasn't expecting conner to ever come home. >> coming up -- a cheater, a liar, but a killer? i mean, really, who else could have done it. >> i'm glad you asked that question. >> when "dateline" continues. when "dateline" continues ♪♪ and even when things go a bit wrong, we've got your back.