A 'regime' is usually a term for an illegal government or a government that does not value or protect the rights of the people.
In the early 1970s Salvador Allende was fairly elected as the president of Chile. Indeed, he became the first 'socialist' to be elected president of any country. (A socialist is someone who opposes 'capitalism' - so a socialist believes that the state should provide goods and services to the people and control the business production of the country.)
After Allende became president, US and English companies became quite upset because Allende started to nationalize foreign business operations. Foreign businesses had been making lots of money from the Chilean people, but not contributing much to the Chilean economy. So Allende took over these businesses in the name of the people.
President Richard Nixon and Secretary of State Henry Kissinger then ordered that Allende be assassinated (killed) and the CIA (the American spy agency) helped General Pinochet overthrow the Chilean government. Salvador Allende was killed as he fought to protect himself and his government.
After Pinochet took power, he tortured and killed many people in Chile and turned the country into a dictatorship (no freedom) for many years. The people of Chile finally overthrew the dictatorship but Pinochet was never thrown in jail for his crimes.
Here is a story about 4 men who were killed by Pinochet and how they are finally receiving a proper burial.
Vocabulary to help you understand the article:
buried - to have one's corpse (dead body) placed in a hole and then covered with dirt
the remains - same thing as the 'corpse' - the dead body of the person
a grave - the place where corpses are buried in a cemetery; in this case, after they were killed they were just dropped into a hole in the ground with no indication that they were there. I am not sure how they were found in 1992 and I am not sure why it took so long for them to be properly buried. I think it took a long time for the dead bodies to be identified.
a coup - when the military violently takes over a government. This coup was supported by the US government at the time because President Allende was considered to be a socialist who was taking over foreign businesses and giving them to the people
executed - killed
firing squad - when soldiers fire their guns at a person in a formal procedure to kill the person
forensic tests - medical tests done on corpses to determine the person's identity, cause of death etc.
a caravan - a group of travelers or a group going to a destination together
notorious - famous for negative reasons
a delegation - usually a government group appointed by a president or other leader to accomplish some goal
provincial - away from the major cities
opponents - those who did not support the coup/takeover