Passing ID of User (owner) who starts business process

Hello, 

to achieve this you can create a process parameter of Lookup type for Contact object (Lookup field), and fill in value of "Current user contact". then you might use this parameter wherever you need the users id, worked like this for me in test enviroment 

thanks for reply but I does the current user contact change during the business process. I only want the ID of the user who started the business process. At the point in the process I don't want the current user contact but the user who started the process.

There is probably a better solution but in the end I just created a lookup field on the object which recorded the current user at point of the business process starting, and used that later in process.