My grandparents house got broken into last night serious help please

As the title says the worse thing happened last night to my grandparents who are almost 70 years of age. Some vile disgusting human broke into there house while my grandparents where away visiting my auntie. My grandparents had there life savings in the house ( they had a significant amount of money there we encourage them to put it into a bank account but they were stuck in there own little ways and believed it was safe in there house as they stored it there for years) only close family and a very few number of family friends knew about the money been there plus the location in the house they hid it in. When my grandparents got home they discovered there kitchen window had been broken and they instantly called the cops the only room that was damaged was the room where the money was kept not a single other room was touched. We as a family are 90% sure it is someone close to the family who done this awful crime. Sadly we can’t go pointing fingers at anyone till we know for sure. Investigators looked for fingerprints there was no results. We checked cctv and there isn’t anything showing up on that either. My heart is broken watching my grandparents go through this especially with my gut telling me it’s someone very close to the family who done it. Does anyone have any ideas on how we could catch this person we are truly at a dead end but not willing to lose hope that we might still catch this person and the cops don’t seem to be doing much