First, I am very sorry for your loss.  I am not an attorney, but this is what seems logical to me.  If there are signed legal documents naming you as power of attorney and executor of her will, you need to find out if the change of beneficiary was done legally.  Are there legal documents with this in writing, signed by your sister, witnessed  by someone who is not  a party to the action (has no financial stake in it) and is that paper notarized? (A state notary seal or stamp will be on the document)  Or was a simple change of beneficiary card filled out that was supplied by her employer?  When was the change made? Can you verify your sister's handwriting? Is it her signature?   Was she in the hospital at the time of this change or was she at home?  Whether in the hospital or at home, was she  under the influence of narcotics such as morphine or other mind-altering drugs?  How many days before your sister's death did she confirm that your mother is the beneficiary?  Also, did she have a  Last Will & Testament that was drawn up by an attorney?   Or did she write her will in her own handwriting -- this is called a Holographic Will  -- and can be an acceptable document.   If she had an attorney draw up her will you should contact the attorney immediately and explain this latest turn of events.  He or she will probably not charge you under these circumstances to help you.  If there is no attorney of record, you need to talk with a licensed attorrney who specializes in WILLS & TRUSTS.  Any reputable attorney will likely be willing to give you the advice you need over the phone in a brief consultation,  free of charge if you explain the situation.  He or she would know exactly what steps you need to take.  Just be sure that you speak ONLY to a specialist in WILLS & TRUSTS.  You can find a good attorney in your area by going to www.martindalehubbel.com.  There is no fee for a referral listing.  You just fill in the required fields and depending on where you live, an attorney should come up in your general area.  A phone call is probably all it will take and you'll know what to do.  But before you call teh attorney, make sure of your facts.  Be able to answer all the questions I've posed to you in this email.  Don't get into a big complicated story, all he or she wants to know are THE FACTS.  Respect the attorney's time by being concise and getting right to the point.  

One thing I would do is to contact the insurance department at her employer and ask for details about when the change was made and how it was made, i.e., a legal document or a short form or card.  You are her Executor and Power of Attorney so you have a right to this information.  Her signature could have been forged, or she could have been coerced into making the change.  Brain cancer can affect the mind and a person's ability to understand their actions.  Tell the employer's insurance representative exactly what your sister told you and that you want to put a hold on any payout until you can verify that this was your sister's actual intention.  Don't accuse the landlord of fraud, just tell the insurance rep that your sister was in the final stages of brain cancer when she made the change and you question whether she intended to change the beneficiary to her landlord.  

Frankly, I am a bit surprised that the insurance person at your sister's work would make this change without verifying that your sister actually signed this form and intended in making this change.  But these things happen. Perhaps she didn't know your sister's condition at that exact time.  Or she may not know that certain drugs she was taking could affect her judgment.

I've given you a lot of information so if you need any clarification, please let me know.  The most important thing you must do right away is to contact the insurance representative and let them know that you are questioning the legality of this beneficiary change so that they will not pay out the policy benefits right away.  You should have done that immediately when you found out about this change.  Don't delay!  Then you call an attorney.  If you need help finding one, email me with your location and I find one for you.  Good luck and let me know how it all turns out.  My personal email is evancummings@q.com   Evan

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