Short answer. Most likely as a breach of trust, not as a crime against your employer. Article 282 confines that fourth ground to offences against the person of the employer or his family. Taking supplies is ordinarily charged as fraud or wilful breach of trust, or as serious misconduct.
What the law says
Commission of a crime or offense by the employee against the person of his employer or any immediate member of his family or his duly authorized representatives
Labor Code, Article 282 — Just Causes For Dismissal. Read the full provision →
What the law says
Fraud or willful breach by the employee of the trust reposed in him by his employer or duly authorized representative
Labor Code, Article 282 — Just Causes For Dismissal. Read the full provision →
The ground about crimes is narrower than it looks
Article 282 allows dismissal for the Commission of a crime or offense by the employee against the person of his employer or any immediate member of his family or his duly authorized representatives. The words that do the work are against the person. That ground is aimed at an assault, a threat, an act directed at a human being — not at an offence against company property. An employer that fits your case into this paragraph has picked the wrong one, and the mismatch is worth pointing out, because it is not for the worker to guess which ground was really intended.
Where taking supplies is normally placed
The provision that fits is Fraud or willful breach by the employee of the trust reposed in him by his employer or duly authorized representative. Some employers instead invoke serious misconduct, the first ground on the list. Either way the label is not a formality. Each ground has its own elements, and the employer has to prove the one it charged you with. Read the charge memorandum carefully and note exactly which paragraph it invokes, since a case built to prove one ground does not automatically establish another.
Breach of trust is not automatic
The article speaks of the trust reposed in him by the employer, so the ground assumes there was trust of that kind to begin with. It also requires the breach to be willful. An honest mistake, an understood practice of taking scrap or discards, a supervisor's permission, or an item that was never actually missing are all answers to the charge rather than excuses for it. The value of what was taken is not decisive on its own either — what matters is whether the elements of the ground the employer invoked are made out.
What to secure while it is still available
Ask for the charge in writing if you have only been told verbally, and keep every version of it, because the ground stated at the start is the one the employer must stand on. Preserve anything that shows the practice in your workplace — inventory and gate-pass records, the person who authorised the release, messages approving what you did, and the names of co-workers who did the same thing without consequence. If a separate criminal complaint is filed, treat it as a distinct matter with its own standard of proof; the two proceed independently of each other.