Write down your suspicions, put it in an envelope and ask it be put in the chart. Mark for the doctor only...confidential. And explain that you have contacted the police and who the suspect is in your mind. And that you don't want anyone to know as you fear retribution.
Believe it or not, this is not all that unusual to have to go around others in a family. My father-in-law was an alcoholic who drank himself into a coma. Everyone in the family was in denial and no one told the docs how much he drank. they were doing all sorts of tests to figure out what was wrong. I took a nurse aside and whispered to her that he was a heavy drinker who had been on a binge during a bad snow storm and that I suspected that was behind the coma.
Within 2 hours, they had the confirmation and started the appropriate treatment.
Happens a lot...but if you suspect attempted murder, you need to move fast and quietly.
good luck...........Jenny