Rule #10 - Never get personally involved in a case.
McGee also broke Rule #10 when his sister showed up on his doorstep. She was covered in blood and unable to remember the last several hours.
She was involved in a sailor's death, and the reason was difficult to figure out because she was drugged. As a result of the temporary amnesia, it was believed that she committed murder. McGee conducted a preliminary investigation without telling the rest of the team (thus also breaking Rule #15: always work as a team), and was eventually caught. The rest of the team then continued the investigation and exposed the sailor's real killer.
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