Why doesn't Jane simply record the voices of all the 7 suspects (without them knowing) and play it to Rosaline , as she had sexual relationship with RJ and talked to him she might recognize his voice.
I think RJ is the one who looks more likely to be not.For example Bob Kirkland- we think that its too obvious that he's Red John, but think about it - when Bob asked the man in the hospital if he recognizes him, the man said no.Maybe RJ has made a plastic surgery , but he still improves his new voice and act so he wanted to know if hes doing it well by asking the man if he knows him.The man said no and RJ doesn't need him anymore so he killed him before he could tell PJ Red Jone's previous identity.There was no smiley face because the nurse knew who is the only one who had entered in that room.So RJ made sure it doesn't look like a murder and especially from him.