Here’s the sentence: “Dozens died, but the scorched-earth policy backfired, encouraging targets to take their chances with the law; one witness at Buchalter’s eventual murder trial in 1941 agreed to testify only after being shot in the head on Buchalter’s instructions. Buchalter was convicted despite spending an estimated quarter million on his defense.”
The original useage is in warfare: If the enemy is about to take land from you, you destroy it yourself (by burning fields, etc., hence the name) so that the enemy won’t be able to derive any benefit from it. Alternately, an invading army might scorch the earth as they move, so that when the enemy farmers move back in after the army has moved on, they won’t be able to support their own army at the front. In American history, Ulysses Grant was famous for this tactic, and I think the term may have been coined in reference to him.
I was fairly certain that the tactic was first named after Russian actions to counter the advance of Napoleon, but I can’t seem to find a cite (suggesting that I am wrong, maybe).
I don’t know whether that was when the tactic was named, but it’s been used for millenia - Tamerlane is notorious for having been particularly thorough in his use of this tactic.