Rashi on Deuteronomy 24:7/רש"י על דברים כ״ד:ז׳

1כי ימצא IF [A MAN] BE FOUND [STEALING …] — Found when doing so by witnesses and after legal warning. This, too, is the meaning in all cases where a form of the verb מצא is used in the Torah, under similar circumstances (Mekhilta; Sifrei Devarim 273:1).

2והתעמר בו AND TREATS HIM AS A SLAVE — he is not liable to the death penalty until he uses him as a slave (cf. Sifrei Devarim 273:5; Sanhedrin 85b).