This article explains how to determine which user initiated a SharePoint event.

Normally, one could use the "Originator" to determine which user started a process. A SharePoint event however, is fired under the "ApplicationPool" account of the SharePoint site, and not the user who initiated the event. Therefore the ‘modified by’ field changes as soon as K2.net™ 2003 performs any action on the document.

To obtain the username of the person who initiated the SharePoint event, follow the steps outlined below:
1.  Add a new column in your SharePoint document library by clicking on the "Modify Settings and Columns" link and selecting the "Add a new column" link.
2.  Specify the column name and select "Calculated Value" under the "Default value" option. Set the value to "=Me", as indicated below:
 
 
3.  When a document is uploaded into SharePoint, the user’s name will automatically be populated in this new column.
4.  The new column’s value can now be used in the K2.net™ 2003 process when using a SharePoint process template wizard, as illustrated below: