Donald Gennaro was a lawyer tasked by several investors and an insurance company with doing a complete security check on the yet to be opened Jurassic Park, following the untimely death of a worker at the hands of a Velociraptor. Gennaro was a cowardly man and overly concerned with both security and his employers, until he gazed upon a full-grown Brachiosaurus and became concerned with making as much money from the park as possible, to the extent of charging anywhere from $2000 a day to $10,000.
He accompanied Doctors Alan Grant, Ellie Sattler, Ian Malcom and John Hammond's grandchildren, Lex and Tim, on the first official expedition around the park and followed the scientists out of the automatic jeeps to examine a sick Triceratops despite near-constant worrying, and was the first to suggest returning to the cars when a hurricane began to move in. When systems began failing around the park, and the jeeps lost power outside the Tyrannosaur paddock, Gennaro lost his head completely at the sight of the T-Rex and fled his car to hide in the nearest restroom, abandoning the terrified Lex and Tim.
When the Rex broke out of her paddock and attacked the cars, Gennaro remained relatively safe in his toilet cubicle until the carnivore crashed through in her search for Ian Malcolm, leaving Gennaro, terrified and sitting on the last standing toilet. He was swiftly ensnared in the hungry dinosaur's jaws and devoured whole.