but who would want to kill fred engel?d a clue. ♪ narrator: evidence at the scene of fred engel's murder appeared to indicate his killer was lying in wait, that he knew where fred would be and at what time. this was a particularly vicious crime. it was the type of crime that, in my opinion, happens because someone knows someone. narrator: when fred's wife, sherry, found out what happened, first responders nearly had another emergency on their hands. thomas: she became very hysterical, disbelief. she passed out. they were able to revive her, but she wasn't the same. hawes: it was heartbreaking to watch someone process and go through that instant grief of understanding that their loved one, their husband, has passed. narrator: when she could finally communicate, sherry said she had no idea who would want to kill fred and freely gave permission for police to search her house. we're looking for anything that can help tell us what happened to mr. engel. does he have a beef with any of the neighbors in the area? has any business

engel. the cellular data definitely shifted the direction of the investigation straight at her. richardson: i've described it over and over again as a busted lamp or a busted vase. the forensics is the glue that sticks it all together. cestare: that's what turned the whole investigation around to focus at her, to focus at timmy. that's what also told us there was no other players involved in this other than those two. >> focus at heart, the focus of timmy that's what also told us there was no other players involved in this other than those two up next, a young couples road-trip ends in murder. >> that wasn't long before everything turned to help what was done to that was so horrified. police have plenty of evidence, but can't connect their victims to a killer. where did cross paths? >> and what exactly happened? those questions finally get answered? >> after technology available to anyone on the internet. greg's the case wide-open in the summer of 1987, a young canadian couple had just start