The thoroughly unlucky Dr. Trimble is a Bartok Industries scientist of minor importance and with little to no connection to Martin Brundle. He did participate in the ill-fated teleportation experiment that deformed Martin's golden retriever, but nonetheless, it is clearly Bartok that Martin is after when he breaks into Bay 17. Not that this saves poor Trimble.
In an effort to get away from both the ill-tempered fly monster and Bartok's triggerhappy security guards, Trimble hides up on a shadowy catwalk high above the laboratory floor. When Scorby is hunting for Martin in the dimly-lit lab below, he sees movement up on the catwalk and sprays the vicinity with gunfire. Of course, it ends up being Trimble, who obligingly falls off the catwalk to his death.