Can a person make beef jerky in his house if he is not frum. if he says his house is 100% kosher and all his utensils are kosher but he does not keep kosher outside of his home nor does he observe the shabbos. Can i allow him to make some of this food for me. Can i then eat this food once it is ready?
The Halacha states (Shulchan Aruch Y'D 119:1-7) that if someone is a Mumar Ledavar Echad, a habitual transgressor in one particular prohibition, he does not have a presumption of trustworthiness - a chezkat kashrut, with regards to that prohibition. For example in your case, as you have stated, this person does not keep kosher (eating kosher only in the house is not called eating kosher, it just means he is a mumar leteavon - someone who transgress not out of spite but rather out of desire eg. A mouthwatering ham sandwich that he cant "live without") thus if were to claim that a specific food is 100% kosher, he is not to be believed unless he has a certification from a known Rabbi attesting to the kashruth of the food and that the food is under supervision. This is all in regards to selling food.
However, in regards to eating at his house as a guest, the question becomes more complicated as we generally assume a person will not serve you something that is not in accordance with your personal standards (S"A 119:1) However this is not a hard fast rule and a competent Rabbi should be consulted.
You also mentioned that this person does not observe Shabbath. It depends, if he transgresses publicly, then that would prohibit you from trusting him at all, even on much more minor transgressions, however if he only transgresses privately, then again the question becomes more complicated and a Rabbi should be consulted.
This should not replace asking a Compentant Halachic Authority