As more time goes on, the more I return to my original theory - failed kidnap for ransom.
This person targeted NG, knowing SG was her daughter and could extort the family for millions. But NG had a medical event or this person was too rough with her and she passed away. Then they panicked and tried to stick to the plan, but couldn’t provide proof of life. JMO
The fact there have been no further arrests related to the ransom notes is important IMO. Whoever sent them clearly spent an extensive amount of time and effort making themselves untraceable.
Unfortunately, with all the information regarding ancestral DNA and the extreme media coverage, I’m concerned this person may have taken their own life or left the country. JMO