"Investigative" is a word in ENGLISH

An internal auditor for a manufacturing group was concerned about anomalies in stock levels. He thought someone might be pinching stock but he couldn't prove it. He had his eye on one shifty-looking individual who every day drove his old truck out of the factory with the load covered by a tarpaulin. Time after time the auditor stopped the bloke, made him remove the tarpaulin and then inspected the load. On every occasion there was only scrap metal in the truck which the driver said he was taking to the tip. On three occasions the auditor made the bloke remove the tarpaulin and then unload the scrap in front of him, suspecting that there might be stolen stock hidden underneath. Nothing. He could never find anything amiss.After a few months of this the auditor was offered a better job elsewhere and resigned. A few weeks later he was drinking in a pub when the shifty character walked in. On a n impulse the auditor went up to him and said, "Look, I've left the company, I'm not interested in taking it any further and I won't shop you, but I just have to know. What were you taking?"And the bloke said "Tarpaulins."