Thank you for your interest in Bizagi.
To create a New Case from an external application to Bizagi, you may use the createCasesAsString web method available from the WorkflowEngineSOA web services (http://wiki.bizagi.com/en/index.php?title=CreateCases
). In this invocation, you may also send the information of the user creating the case, in which scenario it could be the same user who will be in charge.
This would avoid the need to define explicitly a participant, mainly because by default if no assignment rule is specified, the next task will be assigned to the case creator.
Another option is to define and use and assignment rule, in which you can model the idCostumer (a reference to a Customer entity) as a user property (http://wiki.bizagi.com/en/index.php?title=Organization#How_to_Create_User_Properties
Through this approach, this property could be used from inside your rule to return the user expected to work on this case.
Also, you can see some assignment examples at: http://wiki.bizagi.com/en/index.php?tit ... t_Examples
Bizagi BPM Suite Support.