In cybersecurity, the absence of data can be just as dangerous as the presence of malicious activity. This white paper explores the concept of “dark periods”—gaps in logs, artifacts, or digital evidence—that leave investigators blind during critical incidents. Drawing lessons from both high-profile criminal cases and breaches like the APT38/Bybit attack, it shows how attackers exploit these blind spots to evade detection. The report will highlight essentials for preventing catastrophic investigative failures, including: