Shulchan Arukh, Yoreh De'ah 2/שולחן ערוך·יורה דעה ב׳

1The shechita of a non-jew, (the animal slaughtered has the status of a) nevilah (animal which was not shechted or shechted improperly). Even if he (the non-Jew) was a minor and even if the non-jew does not worship idols. Rema: {For example, a legal resident (a non Jew who does not worship idols and lives among Jews)} and even if others watch him.

2If a wanton sinner who eats a nevilah* and deliberately (slaughters), if a Jew first checks the knife that he is given, only then are we allowed to eat from what he slaughtered even if he slaughters alone (only) if he knows the laws of slaughter. However if the knife is not checked from the beginning, it is forbidden to eat what he slaughtered until we check the knife at the end. And if it’s not given to him in the beginning in order to slaughter, even if a trustworthy person stood over him to assist, without checking the knife from the beginning, we don’t rely that the knife was fit to slaughter.(even if you plan to check it at the end)

3A wanton sinner * who intends to slaughter, even if he swears that he slaughtered with a good knife he is not believed....(*carcass of a kosher animal not killed in accordance with Jewish law and therefore forbidden for consumption.**a ”mumar leteiavon” does not mean an apostate, it means a wanton sinner who sins out of lust or desire, not out of heresy)