It's been connected to the internet, if I turn the internet off, is there a way my BTC can be stolen without physically taking my pc?
no man..your btc will be safe if no one has physical access except you , provided you are offline ..
if any key logger is installed and you are offline no man can hack your stuffs but the scene can be different if key logger is installed and you gonna be online..
so better be offline and don't let anyone touch your pc..