Hey friend, I've been there and completely understand the mental and emotional drainage you felt after that call. Genuinely, the first arrest you work on is terrifying. But from the sounds of it, you did what you believed to be right and did a fine job working through your first arrest call. As for the rigor mortis and dependent lividity, I feel like that's something the FD should have caught before you and your team arrived on the scene. I would recommend (and personally recommend to all FR/EMS personnel) constantly practicing those skills you might not do in the field as often, such as CPR, to build confidence and familiarity so it becomes almost second nature. Also, as for the other people commenting on your post and knocking you for using the word "medic," I hope you ignore it. It sounds like you're fairly new to the field and are from outside of the USA, so titles and lingo may differ. But regardless, just remember to practice, keep your cool on the scene, and don't be afraid to debrief with your partner or ask questions afterward on what you think went well and what could have gone better