So called Disinherited Heir but no proof.
2 attorney answers
There is a huge difference between a Will and a Trust. But regardless, if the estate has been closed, you have a huge problem. You will need to hire an attorney on this in CA and seek relief/remedies in a probate court.
You are ABSOLUTELY entitled to see a copy of the will or trust. Contact an attorney and start by giving them the property address. The deed may show if there was a trust and who the attorney was. The attorney can also write a demand letter to your sister advising her of the law. If all else fails, you can file a Petition in court to get access to the trust.