Perhaps LE is directing ER in what to say. It is not an impossibility, Imo.
Also, that quote about "family members are still cooperating" may or may not include MR. It may mean what it says, that family members continue to cooperate, but does not specify ALl family members, as it easily could have done.
As far as ER showing her frustrations and perhaps, her true feelings about MR, again Desiree Young comes to mind. A lot of people felt she was wrong in accusing Terri Horman publicly, as far as helping the case, but understood her need to speak her frustrations aloud. She had background knowledge that we did not have that caused her to believe that TH harmed her child. For a long time, she felt that Kyron was being "held", as that is as far as her brain would let her go. Eventually, she seemed to come around to the concept that he was probably not alive, but it took a very long time. I think Elaine is going through much the same thing that Desiree is and has been enduring for more than 2.5years.
MR not communicating with, at least, CR is total BS, IMO. In this way, he shows his true self to me. I do not believe he cared much about Dylan until ER decided to take the new job and move away. If so, ER would know this better than anyone. I think she has been very restrained, actually.
Everything about LE's manner in this case points to their suspecting MR, as far as I am concerned. If so, I hope they are able to eventually charge him.