Raise the alarm. Report the incident to the charge nurse, the nursing supervisor, risk management, and the attending physician. However, be forewarned: your entire allegation is based on something only your mother witnessed and it occurred at night. Everyone you tell will (1) be blown away by the strangeness of it; (2) react first by be suspicious as to whether your mother's account is reliable ("Did she dream that this happened?")
You will likely never be able to hold the nurse accountable because of the lack of evidence and the lack of an injury to your father. However, to protect your father over the next few days, you need to sound the alarm and also stay with him at bedside.
What you are describing is not malpractice, it is an intentional act that may be criminal. First, your mother should report it to the hospital and second, should consider reporting it to the police and/or prosecuting attorney.
This answer is provided as a public service for informational purposes only. Providing this information does not create an attorney-client relationship. As with all legal matters, you should contact an experienced attorney in your geographical area to discuss the law specific to your state. For more information, see www.hendricksonlaw.com.
File a complaint with the local police department. Then contact the nursing board and file a complaint against the nurse. Then file a complaint with the Dept. Of Managed Health Care and any agency that regulates the hospitals.
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