At trial in 1921, expert witnesses disagreed about Bullet III. “[F]irearms identification in 1921 was in an embryonic stage,” notes forensics investigator James Starrs. The controversy surrounding Bullet III intensified after the trial.
Could you please explain why there is not used in the first sentence the definite article while in the second one it is so. – Maybe my second question is irrelevant for this site… but what does it generally mean when the part of the quoted text is in square brackets (like above "[F]irearms")? Is that from the reason that in the original text it is written "firearms"?