I think these agreements probably require all DAs in the crime areas to give immunity. We have a similar case regarding immunity agreements here in southern Ohio.
The foster parents of Marcus Fiesel (Liz and David Carroll)) along with their live in girlfriend (Amy Baker) left him bound in a closet while they went to a family reunion for a few days. When they returned he was dead.
They claimed the boy was lost in a local park meanwhile Amy and David took the body to the country and burned it and on the way home dumped the remains in the Ohio River. After weeks of the community searching for the boy Baker agreed to testify against the Carroll's in exchange for immunity and they were both convicted of murder.
The local DA got immunity agreements with the DAs in Ohio but apparently did not consider that the Ohio River where the remains were dumped is technically part of Kentucky. Many people were angry that Baker got charged with nothing for her part in the crime. The DA from Maysville located on the Kentucky side of the river charged Baker and said Kentucky was not included on the immunity agreement. This case is still going on.
http://news.nky.com/apps/pbcs.dll/ar...0103/712140419