They used her trash to narrow it down further
New testing showed as you said that her family were likely relatives to the dead baby
How they already had DNA on one of them who knows could be many reasons from crime to hospitals or any other DNA gathering source
Suspecting the mom as the killer is pretty reasonable once you find out who she was ..either her or her family unless she was held hostage by baby killers at the time
The circumstances is definitely more to the story
Hope ya'll are well and safe from the creeping crud.