Okay, this would have to be very well explained to get accepted. Firstly, how were his parents killed? If they're pureblood wizards you need to come up with a good explanation. Secondly, how old was he? If he doesn't remember his parents or being adopted he would have to be under a year old (my earliest clear memory stems from when I was 15 months old, for example) and then you will have to explain why he wasn't taken in by an aunt, uncle, grandparent or family friend. I honestly can't see right now how a pureblood wizard would effectively be abandoned with muggles - there have been a few cases in the UK of newborns being left outside hospitals because the mother can't cope and every time there has been mentions in newspapers and even the national TV news where they try to find the mother and make sure she's okay - so the MInistry would likely find out about it. In short...there are a lot of plotholes here that will need to be closed. I'm not saying that it's impossible, just bringing up a few things you will need to think about.
Hope that helps a bit
~ Carys