I found a jar in my little sister's closet with two fingers in it?

They were preserved in formaldehyde but they are human fingers. She also had a box of human hair in there. She says she bought it for weaves but it doesn't look like hair weave hair because there's not enough of a single color/type/length for a weave and it looks like it was just cut off of people. Should I tell our parents about this? I feel bad breaking her trust and she told me not to tell our parents. She is 14.