Blood or adopted

I'm sorry for your loss.  Adopted children are treated the same as biological children under the probate law, if that is your question.  If someone dies without a Will, the law of intestacy for the state where that person lived applies.  If your mother did not leave a husband/domestic partner, then her probate assets should be divided among her living children as well as the children of any deceased children.  Probate assets are those that were in your mother's name alone with no named beneficiaries.  Life insurance, for example, is not a probate asset usually because there is a designated beneficiary who is to receive the policy payout after the insured person died. It sounds like your mother had a joint checking account with your sister.  This also is not a probate asset as joint accounts are considered to be owned by both people, no matter whose money is was originally.  Upon your mother's death, the account became your sister's automatically.  If you are concerned about getting your share of your mother's personal property since your sister has the key, I recommend sending her a written request to visit your mother's home again or even requesting certain items.  As you both are dealing with your mother's death, it may be helpful to put aside judgments and criticisms in favor of understanding that grief affects all of us in different ways and that your relationship may be more important than this temporary situation of dividing your mother's things.