Courier has developed a system to expedite support ticket investigations by integrating AI code exploration with human analysis, achieving resolution times up to four times faster for complex issues. Their methodology allows support engineers to run an AI agent that examines the codebase while the engineer simultaneously examines the customer's actual data, enabling quick identification of discrepancies. The system leverages tools like custom investigation agents and sample apps to test hypotheses without accessing customer data directly. The process involves a structured workflow that documents each investigation in detail, building a searchable knowledge base that aids future inquiries. By combining the agent's rapid code exploration capabilities with the human ability to interpret real-world scenarios, Courier effectively reduces backlog and enhances efficiency in handling support tickets. The parallel investigation model is continuously refined to optimize the synthesis of AI and human insights, providing a more accurate and efficient problem-solving approach.