d. In the oil theft case discussed in the text and the video, the fraud investigators conducted a week-long invigilation. The results from this period were compared to the results taken during the weeks immediately before and immediately after the invigilation. Briefly describe invigilation? Was this an effective method to use in this case? Why?

d. In the oil theft case discussed in the text and the video, the fraud investigators conducted a week-long invigilation. The results from this period were compared to the results taken during the weeks immediately before and immefliately after the invigilation. Briefly describe invigilation? Was this an effective method to use in this case? Why