Salam brothers and sisters, I want to ask, what is the ruling on using leather products from animals that is not slaughtered in sharia method ? From my readings and my opinion is that, we can use leather products of animals that is permissible for us to eat(like cow, sheep, etc). For animals that died of unnatural way or not slaughtered in shari'a method, we can still use it as long as it is TANNED.

So, here comes another question. HOW DO WE KNOW IF IT IS TANNED OR NO ? I couldn't find any sources that let us know if it TANNED or no. The only sources that that I find is from a scholar in our country and he explains very well. I tried to find an 'international view' with regard to this matter in English but couldn't find it.

Could it be that I am overcomplicating things like maybe I am naive? Because to know that one leather products is TANNED or no is simply just by looking at the leather products, if there are no blood, no meat, no dampness, or any other sign of filth, then we can consider that it is TANNED.

If I am naive, why I didn't find any sources or any link that explains this matter in detail ? So, in summary my questions is :

1. HOW DO WE KNOW IF IT IS TANNED OR NO ?
2. Can non Muslims perform tanning process ?
Thank you.