Although information technology has improved our living standards, it has also provided criminals new ways to commit crime. Digital crime includes identity theft, online piracy, hacking, and terrorism. For combating digital crime, new techniques and tools emerge frequently in digital forensics. On the opposite side, cyber-criminals develop counter-techniques called anti-forensics, which aim to disrupt or manipulate forensic analysis of crime. This thesis investigated the effectiveness of some representative anti-forensic tools for data hiding, artifact wiping, and trail obfuscation. We found they varied considerably in effectiveness and a variety of countermeasures can be used against them.