Imagine how large a department such as SDPD is and the many employees of the district attorney's office. Surely no one thinks that 100% of these folks are saintly. I wouldn't be the least bit surprised to find a handful or more that are involved in swinging and other shameful acts in their private lives.
If one important person was very worried about exposure, that's all it would take. Some people act like corruption stops at the police department or DA's door and any consideration of hanky panky is just wrong. Puhleeeeeeze !!!
The fact that the blood drop on the jacket was never properly photographed and that the forensic specialists were instructed to not use 35mm is about as suspicious an act as I can fathom.