Can a nursing home open patient mail and take checks?

IMMEDIATELY go to the local Post Master of the post office. File a complaint against the facility and heaven help them - they are committing a federal crime. I found out that is how to protect oneself from facilities opening and taking mail. I had mail addressed to me which contained medication as I handle 99.9% of everything myself and they said it had to go to the nurses. I threatened them with a postal complaint in violation of federal laws. Never, ever did I ever have mail withheld again. And it does not cost you anything to do that. You can talk to the p.m. and then tell the facility you will file a federal complaint for mail violation. That should shake them up and make them stop. And may be you could have all of the mail sent to YOU, not to the patient.

UPDATE We confirmed today that the resident, my cousin, did NOT sign anything granting the facility permission to open her mail. The check was put against her private pay bill and we have not argued with that. We believe the woman in charge of money (billing and the residents' in house bank) plucked the check from the mail before it could be delivered to my cousin. I have not confirmed it was her with Administration because voicemails and emails are unreturned. The 3rd party billing office said she is one who processes money. The same woman told my cousin, "the check is not in the building" more than a week after she had taken it. The administrator told me, "no one has seen the check" and that i should contact the state and check the address. We hope the State will be able to provide a copy of the back of the check to see how it was endorsed.
We will follow up to confirm how/who/what happened and politely but firmly stress this should not happen. No other government checks like this will be forthcoming. And i will stress to her friends to be cautious when mailing her anything. Thanks everyone for your input, especially AlvaDeer, you are a love.

Thanks for the update.

Alva: Agree with your post since we found out on 9/3 that the check was used in the proper way. Thanks.

ANOTHER UPDATE: got a copy of the back of the check, it is NOT endorsed, No signature, no "for deposit only", no account number. And it has the usual "Do not write below this line Know your endorser" Hysterical as it is not endorsed. It has a horizontal line with the words "electronically presented". I assume that means the "paper" check plucked from my cousin's mail by the nursing home accounting person did not continue thru the banking system as a "paper" check but was converted to an electronic payment, Thus no eyes to "know your endorser."
And yes I am still "queasy" about the staff going thru resident mail and taking checks. No explanation from the nursing home as to why they looked her in the eye and told her the check wasn't there. . I hear my dad to this day -"it's the principle of the thing!"