The spelling, grammar and punctuation of the memo is very poor, much like some of the other memos found in the hospital. Because of this, they're all most likely written by the same person. The author in question is probably Joseph Barkin, a mental patient first mentioned in some patients records found in the reception office on the first floor of the hospital. Also, the cell where the message is located is most likely his due to a message which can be found on the wall outside the cell.