In the last few months of Project Loco, the government was getting less enthusiastic about Doc's creations. With limited to no success with integrating them into the public, the gov gave Doc 3 more chances to prove his Locomatons can in fact be life like. So, Doc made the last 3, none of which successful.
The second failed loco they called Mark.
At first, Mark seemed to be a success. He had a simple personality, but was genuinely likable. Likable enough for a crew of sailors to hire to help out around the harbor. All seemed well until he received an injury. Apparently a rusted rail pipe fell from a load held by a crane, and impaled Mark through the head. Though he survived the incident, the damage done to his artificial brain was evident, as he became more sinister, unpredictable, and developed an unhealthy obsession with fire. After setting off one near the harbor, he was sealed away, having become too insane.