"An expert is no accomplice. There is no justification for condemning his opinion evidence to the same class of evidence as that of an accomplice and insist upon corroboration. True, it has occasionally been said on very high authority that it would be hazardous to base a conviction solely on the opinion of a handwriting expert. But, the hazard in accepting the opinion of any expert, handwriting expert or any other kind of expert, is not because experts, in general, are unreliable witnesses -- the quality or credibility or Incredibility being one which an expert shares with all other witnesses, but because all human judgment is fallible and an expert may go wrong because of some defect of observation, some error of premises or honest mistake of conclusion. The more developed and the more perfect a science, the less the chance of an incorrect opinion and the converse if the science is less developed and imperfect. The science of identification of finger-prints has attained near perfection and the risk of an incorrect opinion is practically non-existent. On the other hand... the science of identification of handwriting is not nearly so perfect and the risk is, therefore, higher."