Thank you milkymama. I went back and really read the death certificate, likely something that family members even find hard to do. I had looked at another website on death certificates, which stated the death certificates for Washington state were kept at Dept. of County health after 1960. This or another website stipulated all the information that could be on a death certificate, such as even the occupation of the deceased. I read with a view to noting all the types of information. It seems that the death certificate was made out at the hospital. I see the signature of an attending physician on the certificate. Then it likely gets transferred to the County Dept. of Health. They probably don't check it out too much. It's doubtful that they would contact the Dept. of Health in Bakersfield, California where Becky was born.
I am back pretty much where I started from. It's not getting me any closer to understanding how Lori Kennedy had chosen this particular identity to take over. If I was Ian Rankin's character, Inspector Frank Rebus, I would not give up. Tiny clues are out there, and he keeps scratching until he finds them, in the character of Inspector Rebus.