Breakdown of Non credevo più che avessero intercettato il codice.
non
not
avere
to have
più
more / anymore (with 'non')
credere
to believe
Questions & Answers about Non credevo più che avessero intercettato il codice.
Why is avessero intercettato in the subjunctive mood?
The main verb, credevo (I believed), expresses a personal opinion or state of mind. In Italian, verbs expressing belief, doubt, or emotion almost always require the following verb connected by che to be in the subjunctive.
Why do we need the pluperfect subjunctive (avessero intercettato) instead of just the past or imperfect subjunctive?
This is the sequence of tenses at work. The main clause (Non credevo più) is in the past. The action of intercepting the code happened before that past belief. To show that an action happened earlier than a past main clause, you must use the pluperfect subjunctive.
If the main sentence was in the present tense ("I no longer believe"), how would the second part change?
If you said Non credo più (present tense), but the interception still happened in the past, you would use the past subjunctive instead: Non credo più che abbiano intercettato il codice.