accused of theft (CCTV)

hi po first of all i would like to thank you in advance for any advice. here it goes, i was given by our HR a notice of explanation regarding the violation of "theft or embezzelement" why? nkita daw kami sa cctv na ginalaw ang mga box na may mga pera. box is situated in a populated area in our office malapit sa exit ng ofis so lhat ng tao mikita ka. did we touch the box yes but this is to check if madami n laman ng box ng department nmin sadly nahulog ang mga pera na barya dun at ciempre ibabalik nmin., we are accused of stealing the money of other boxes na nilagay nmin pr sa department nmin. question is how do we answer this if i would like to pursue a counter charges? sobrang nakakahiya na maparatangan p lng na magnanakaw. after so may years of being a good and law abiding employee.. how would i answer the notice to explain should i answer it? HR ang nagfile ng kaso and HR din ang magdedecide? is it fair, salamat po,,,