I found an unmarked pill in my grandpas augmentin, it was a large white oval pill, no marking,no split to cut, it looks like someone through it in to disguise it with the large white augmentin tablets.

I am concerned for his safety, I told the pharmacy, they looked at it and said just flush it, I told the police, they said to look on pill identifier.

I am uncomfortable with this finding as there is someone in the family that I suspect would like to make him sick or even die as he has been in and out of the hospital for pneumonia because of aspirating thin liquids, which again this person has been caught giving him water, and knows he needs honey thick.

What can I do? What could this pill be?