$25,000 Missing From Our Home. Minor Sibling Involved. Need Advice On What To Do Next.

Location: New York City

My dad kept his savings in our closet in a bag and there was no lock or anything. There was 35k in cash. My little brother (age 12) found out about it 2 years ago and started gradually stealing cash from it. My dad was unaware of this situation. My brother than showed the location of the cash to his friends, also age 12 (he told them its his money he earned by doing a business but not that its my dads money). He then often used to have his friends guard the door while he took money out of the bag that was kept in the closet. Fast forward 2 months ago, my brother noticed the money was gone completely, he thought my dad moved it. But my dad didn’t check the bag often so he wasnt aware of his money missing at all. And then finally 2 days ago my dad found out his money was missing and my brother told us the truth. My brother suspects that the 2 friends that knew about the money stole it from the bag. My brother probably stole around 7-8k based on the calculations of the stuff he has bought over the past 2 years and my dad mightve used 2-3k but theres still around 25k thats gone and unaccounted for. We asked my brother many times if he is the one who took the rest of the money as well and just blaming it on his friends. He admitted to everything but is standing firm on the fact that the rest of the money was not him. It seems he really thinks his friends took the rest of it. We tried talking to the parents of the 2 kids but they were pretty much uncooperative and did not believe their children would do that. They were basically trying to blame it all on my brother. My brother said he noticed his friend buying expensive designer clothes and airpods in the past 2 months(according to my brother, thats when he noticed the money was missing from my dad's bag). What should we do now? What legal actions can we take?