Bava Kama 119a #1: Hashem will wage the [victims'] battle and "Kava Es Kov'eihem Nafesh" (mortally avenge their afflicter). R. Yonah - this is because they cannot save themselves - "Matzil Oni mi'Chazak Mimenu" (Tehilim 35:10). Even though normally the punishment for theft is monetary, there is Misah bi'Ydei Shamayim for stealing from an Oni, for it is as if he kills him. Also, he annulled fear - "Amar Naval b'Libo Ein Elokim" (Tehilim 14:1). Since no people help the Dal, the thief does not fear Elokim - he says, there is no judgment or judge ¹ . Also, the thief knows that the Oni hopes only to Hashem, and that Hashem will wage his battle, for no one else will.

R. Yonah citing Bava Kama 119a #2: Hashem will avenge the thief, i.e. for he mortally afflicts his victims.

Bava Metzi'a 112a #1: Anyone who withholds wages is like one who takes his [own] life (he causes his own death).

Bava Metzi'a 112a #2: Anyone who withholds wages is worthy of death because he mortally afflicts the worker.

Sanhedrin 7a: If a judge takes from one and gives to another improperly, Hashem takes his soul.

Rashi: Hashem will steal the Nefesh of Kove'eihem. Kov'eihem are those who steal from them. In Arame'ic, Kevi'ah is theft (Rosh Hashanah 26b).

Malbim: One who steals from an Ashir or tilts his judgment, since the Ashir has his own power, this is only monetary. Since an Oni has no one to wage his battle, Hashem will do so. Hashem wages the battle of one who has no strength to do so. Then it is not a monetary case, rather, a capital case.