Is it modern or contemporary? In the former case I would like to know who wrote it.
There are earlier references to this song, however, the most complete version of this song I was able to find was this one.
It not only includes much clearer audio than any other version; it also has a speech at the beginning over an instrumental of the song, confirming that the instrumentals and vocals were recorded separately.
The song clearly mentions its author as Luis Checho Gonzalez Jimenez. After some digging, I found a Wikipedia page about a Chilean 70's singer called Luis "Checho" Orlando Gonzalez Jimenez.
It seems that Willy Bascuñan is the composer as well as singer.
The song is Adios Mi General and it was composed after Pinochet's death. Somehow it seems that it is being used by a far right podcast.