Spoiler alert: the husband did it. If you're a true crime fan, this comes as absolutely no surprise to you as the spouce/significant other is always looked at first, but the reason this case didn't go in that direction immediately is because the victim could not be identified. I won't go into the details here, as they are quite gruesome, but the gist is that after finally being able to identify the victim with forensic advancements they were able to determine that Ruth Marie Terry's husband was her killer, and she was not his only victim. For the specifics on the case click the link in the post below!
One more thing of note in this case, is that an "armchair detective" theory has been circulated that some of the last moments of this woman's life were caught on tape as an extra in the movie 'Jaws.' Read more on that theory HERE although I have not seen anyone confirm or deny this since she has been identified and her case considered solved. HERE is a link to the Wikipedia article about her case if you want to dig in even deeper!