Finding out who threw the proxymine

function ProximityMineData::onThrow( %this, %user, %amount )
{
   // Remove the object from the inventory
   %user.decInventory( %this, 1 );

   // Construct the actual object in the world, and add it to
   // the mission group so its cleaned up when the mission is
   // done.  The object is given a random z rotation.
   %obj = new ProximityMine()
   {
      datablock = %this;
      sourceObject = %user;  // <<< this is what you need
      rotation = "0 0 1 "@ (getRandom() * 360);
      static = false;
      client = %user.client;
   };
   MissionCleanup.add(%obj);
   return %obj;
}