Why was Archbishop Oscar Romero martyred?

Oscar Romero was from the country of El Salvador which consisted of about 99 percent poor people rule by a rich and elete upper class that was very right wing. Romero was very outspoken against the government's oppression and persecution of the country's poor. This was taken as a threat to the stability of the ruling class so a death squad, with the backing of the government, arranged for his assassination.