Learn Spanish (Latin America): ¿Es al supervisor a quien implica esta prueba? - Is it the supervisor whom this evidence implicates?

This is a key rule for Spanish cleft sentences. Because the supervisor is a person and the direct object of the verb implica, it needs the personal a, giving us al supervisor (a + el). When you emphasize an element that has a preposition in a cleft sentence, you must repeat that exact same preposition right before the relative pronoun. That is why we also need a before quien.

Why is the word order implica esta prueba instead of esta prueba implica?

In Spanish, it is very common to invert the subject and verb in a relative clause. The phrase esta prueba is the subject doing the implicating. While you could technically say a quien esta prueba implica, putting the verb implica first sounds much more natural and avoids awkwardly separating the relative pronoun from the action.

Could I use que instead of quien in this sentence?

You cannot use just a que, but you could use al que. Because the emphasized element is a person, a quien is the most precise and standard choice. If you prefer to use que, you must include the definite article to match the masculine, singular supervisor, making the sentence ¿Es al supervisor al que implica esta prueba?.

Does the word always translate to evidence?