HOW GENUINENESS OF HANDWRITING PROVED:

   Well-entrenched is the rule that resort to handwriting experts is not mandatory.  handwriting experts, while probably useful, are not indispensable in examining or comparing handwritings or signatures. This is so since under Section 22, Rule 132 of the Revised Rules on Evidence, the handwriting of a person may be proved by any witness who believes it to be the handwriting of such person, because he has seen the person write; or has seen writing purporting to be his upon which the witness has acted or has been charged, and has thus acquired knowledge of the handwriting of such person.  Moreover, the opinion of a non-expert witness, for which proper basis is given, may be received in evidence regarding the handwriting or signature of a person with which he has sufficient familiarity. (Fullero vs. People of the Philippines, G.R. No. 170583, September 12, 2007, Chico-Nazario, J.)