| Evidence Type | Disappears In | What It Proves |
|---|---|---|
| Dashcam footage | 24–72 hours | Exactly what happened at the moment of impact |
| ELD / hours-of-service logs | 30 days | Driver fatigue, hours-of-service violations |
| Black box (ECM) data | Next significant event | Speed, braking, throttle before crash |
| Skid marks & road debris | Days–weeks | Pre-impact speed, evasive action, point of impact |
| Surveillance camera footage | 24–72 hours | Third-party, unbiased view of the crash |