Can you keep money deposited into your bank account by mistake?

You are responsible for any money that is present in your account. If you feel some transaction (a deposit) has happened in your account which you are not aware of, you must notify the bank of the same. If you happen to hold on to this money and it so happens that this money was being used by terrorists and they put it into your account by mistake, you will also be in trouble. So it is better if you intimate the bank reg. this.