I don't have much time to add all i'd like right now...but i do want to say a couple things, coming from someone who grew up with people who had drug and alcohol problems.
Your parents could definitely have been sick and tired of worrying about Elizabeth, sick and tired of always wondering where she was, what was going on with her, if she was alive or not, etc. Being the parent of someone like Elizabeth is exhausting and emotionally tiresome...i say this not to be offensive, but from experience watching my grandmother and grandfather, as well as myself, deal with this same stuff with my mom, who was also adopted at birth. If your parents aren't at fault for what happened to elizabeth, it's very possible they didn't report her missing right away because this was getting to a point of them not wanting to deal with it anymore. Everyone deals with it in their own way, and it's possible your parents had enough already...let Elizabeth be, let her live her life and just "let her go" in a sense. They probably thought she was just off galavanting and were tired of worrying about it. They may have cried to themselves, they may have worried inside of themselves, but on the outside they were trying to just move on and out of the burden of always worrying about a 20 year old who didn't care about herself.
That's if they had nothing to do with what happened to her.
On the other hand, i also think that maybe Elizabeth came home, drunk and/or high...fell asleep in her room or somewhere else, maybe she overdosed and mom and dad just let her go. Maybe they were ready to just have her gone and out of her misery of a destructive life, then "laid her to rest" somewhere...
I'm sorry if this all sounds harsh. I just know what it's like to deal with people like this and what it's like for others dealing with it as well. I'm an observant person, and even at young ages, i saw the emotions my grandparents went through - both my dad's parents and my moms. My dad was an alcoholic. My mom on drugs and alcohol, multiple attempts at suicide....
I begged and begged for my mom to get clean, to come and be with me, raise me, be in my life. She would go to rehab or get clean for a little bit and then be gone again. The come and go relationship was emotionally EXHAUSTING! Finally, at about age 14 i gave up. I stopped worrying about her, i stopped caring about her, i stopped begging her or wanting her in my life. Laura, it really does get to a point where some people just can't deal with it anymore, it gets to be too much to handle.
I would need to know more details, but from what you have given us, i think either your parents weren't involved and just were trying to let her go so that's why they didn't report her right away, or they were involved and thought they were doing the right thing...hiding her, saving face (my grandparents were the same way with my mom! always owrrying about what the neighbors would think
they were different times back then, weren't they..)
I pray for answers for you Laura, it's obviously something that has been eating at you and you need some answers. I really hope and pray that you get them. I hope us here at WS can help, and i thank God for that investigator caring so much about Elizabeth's case.