they only need to show cause to bring her to trial for this crime. she's already confessed to it. i'd assume that's really all they'd need to bring out tomorrow.
The prosecutor is going to present one witness, according to Farese, and he is not going to present any - at least, this was as of a couple of days ago.
Normally, the one pros witness is the LEO who apprehended the suspected perp and/or took the suspect's statement or confession. They waive "hearsay" rules and allow the officer to state under oath what he was told or his report of the events, for the record and not for the truth of the 3rd party statements.
In this case, it might be the Selmer PD officers who went to AL to get Mary and wrote out the arrest warrant in TN, since two different states are involved.