and paying attention to detail in my opinion is what you have to do in each and every case to make sure that you don't miss anything. >> nothing you put on a computer is going to disappear unless it's at the bottom of the lake or somehow destroyed in the fire. it's going to follow you even if you think you have destroyed it. up next, a woman is murdered in broad daylight. >> this is the monster jumping out of the bushes and grabbing you and killing you. >> cell phone records and search dogs provided some leads. >> they were able to track a scent trail to a residential area that was close to the canal trail. >> but if not for some crafty police work and the chance encounter, the entire investigation could have gone up in smoke. >> we have an individual that's still out, walking about, who can do this again. >> i don't know how much scarier it can get. during her lunch break in concord, california, kathy