DisplayName Lookup by UserID

public string CreatedByUserName
{
	get
	{
		if (createdByUserName == null)
		{
			int portalId = PortalController.Instance.GetCurrentPortalSettings().PortalId;
			UserController controller = new UserController();
			UserInfo user = controller.GetUser(portalId, createdByUserID);
			if(user != null)
			{
				createdByUserName = user.DisplayName;
			}
			else
			{
				createdByUserName = "Deleted User";
			}
			
		}
		return createdByUserName;
	}
}