I too am interested in finding out more about Stacey's Mom. She did disaapear at times,but she seemed to return, or atleast make some contact that they knew where she was. Then she turns up missing and never found, no contact.........that is not her MO.
Drew keeps saying he thinks she is alive somewhere..almost like he is certain. I don't buy that from him. I think Drew may have killed her because as messed up as her life had been, it was because of her young children dying, not from some other source. That's why I believe she always continued to come back and make contact with someone in the family.
IMHO, Drew killed her because she was in his way as far as dating and seducing her daughter Stacey, who I believe was probably much younger then he admits when he first started dating her.