The Jurassic Park Security Guard was a novel-only character. He was seen talking with Ray Arnold about the whereabouts of Dennis Nedry. He also tells Arnold that Jimmy, his partner stationed in the lobby, saw Nedry heading for the garage. His quote, "ten, fifteen minutes", was later used by Carter in The Lost World: Jurassic Park.
His body is later found on the second floor by Tim and Lex, who unintentionally locked themselves out of the control room, and eventually use his Key card to get into locked rooms. He was probably killed by the pack of raptors when they raided the Visitors' Center, killing him, Jimmy, and the unnamed control room attendant (whose ear is found).
From the novel:
Guard: No Mr. Arnold.
Arnold: Find him.
Guard: I don't think he's in the building, Mr. Arnold.
Arnold: Then look in the lodge, look in the maintenance building, look in the utility shed, look everywhere but just find him.
Guard: The thing is...Mr. Nedry's the fat man, right?
Arnold: That's right, he is fat. A fat slob.
Muldoon: Into the garage? When?
Guard: About ten, fifteen minutes ago.