In chapter 3, he captures Bob and uses him as a "lab rat" to "conduct experiments". In reality, he is using Bob to steal things he doesn't have access to, to allow him to complete his evil plan known as the Orbital Mind Control laser. However, right in the middle of his operation, Thievious accidentally leads Bob to a secret exit, Bob then escapes to the upper levels and accidentally triggers the Science facility's self-destruction sequence while looking for an "exit button". Bob is able to escape alive, but the resulting explosion blows Dr. Thievious away and destroys the whole facility.
Despite his plans being ruined, Dr. Thievious survives and vows to return later, and tried to rule the world once again by creating Gel-oo™, a mind-controlling jelly, but failed again due to Bob destroying his sewer labs and is arrested by the police.
- Dr. Thievious is scheduled to return in Robbery Bob 2: Double Trouble, making him the only character from the first game besides Bob to be confirmed to return.
- His full name was revealed to be "Doctor Thievious Et Al".
- Doctor Thievious is the only character who doesn't face you on any actual levels.
- It has appeared so that Dr. Thievious was never arrested after the Shamville chapter as he used his mind control helmet to switch bodies with the rat just like Bob when he switches bodies with the headgear dog. Will he return in the next sequel?