República de Kalmukia

So, imagine, if a pesorn was slightly upto no good, for an example, stole few bucks from his such and such…and did alcohols, lied etc….basically, he is not aware of buddhism before, he was living this life..then he learnt buddhism…then he started to reform by taking five precepts….so from that day, would he reform him self just like that, but my real question is this…By being a good human being and taking precepts, can this pesorn reduce his past deeds to some extent?