S.68: Cash credits — Bogus purchases from bogus firm — Forensic Expert’s report showing that account of firm operated in handwriting of assessee and all deposits and withdrawals made in handwriting of assessee —Not availing of opportunity to cross-examine forensic expert —Addition is held to be justified — Addition on account of bogus sales out of bogus purchases will result in double addition — Addition on debit entry to be deleted . [ S.145 ]