This is called Destroying Evidence

Blackwater Worldwide repaired and repainted its trucks immediately after a deadly September shooting in Baghdad, making it difficult to determine whether enemy gunfire provoked the attack, according to people familiar with the government's investigation of the incident.

Damage to the vehicles in the convoy has been held up by Blackwater as proof that its security guards were defending themselves against an insurgent ambush when they fired into a busy intersection, leaving 17 Iraqi civilians dead.

U.S. military investigators initially found "no enemy activity involved" and the Iraqi government concluded the shootings were unprovoked.