Amnesty
Judicial authorities were unable to launch a serious investigation of the incident until April 1995, at which time the military courts responded by filing a petition before the Supreme Court for jurisdiction over the case. Before the Court ruled on the petition, the case was effectively closed by Congress' passage of law No. 26479, which granted a general amnesty to all those members of the security forces and civilians who were the subject of a complaint, investigation, indictment, trial or conviction, or who were serving prison sentences, for human rights violations committed after May 1980.
Prior to the amnesty law being passed, investigations had revealed compromising information. In May 1993, and again in January 1995, some officers from the Peruvian army stated publicly that members of Grupo Colina were responsible for the Barrios Altos massacre. The officers also stated that the head of the Joint Command of the Armed Forces and of the National Intelligence Service (SIN) had full knowledge of the massacre.
Read more about this topic: Barrios Altos Massacre