1
כי ימצא. בְּעֵדִים וְהַתְרָאָה, וְכֵן כָּל "יִמָּצֵא" שֶׁבַּתּוֹרָה: כי 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 d'Rabbi Yishmael 21:16:1; Sifrei Devarim 273:1).
2
והתעמר בו. אֵינוֹ חַיָּב עַד שֶׁיִּשְׁתַּמֵּשׁ בּוֹ: והתעמר 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).