Get collection items in a prior case

I would like to get a list of the collection items in a case other than the current.

I am able to use CHelper.getEntityAttribute for most data points (bool, str, int, etc)

This throws an error for collections.

Additionally - CHelper.GetValueAsCollection does not have a filter to pull the desired information from the single case.

Is there a manner to retrieve collection items from collections not related to the current process?

Data model is as follows

MasterEntity ---->*CollectionEntity---->ParameterEntity

Thank you