Faltaba el distintivo, de ahí que no pudieran identificarlo.

Faltaba is the imperfect of faltar, and here it describes a situation or background state: the badge/identifier was missing.

If you used faltó, that would sound more like a completed event: it was absent / it failed to appear at a specific moment.

So:

• Faltaba el distintivo = the badge was missing
• Faltó el distintivo = the badge was missing/absent at a specific point, or the badge failed to be there

In this sentence, the imperfect fits well because it sets up the situation that explains what follows.

Here faltar means to be missing, to be lacking, or not to be there.

A very common thing for English speakers to notice is that Spanish often structures this differently from English. Instead of saying they were missing the badge, Spanish says:

• Faltaba el distintivo = the badge was missing

So the thing that is absent becomes the grammatical subject.

Because with faltar, Spanish usually makes the missing thing the subject.

So:

• Faltaba el distintivo literally works like the identifier was lacking / missing

This can feel backwards to an English speaker, because English often prefers something like they didn’t have the badge or the badge was missing depending on context.

The verb agrees with el distintivo, which is singular, so we get faltaba.

Distintivo can mean something like:

• badge
• identifying mark
• insignia
• ID marker
• distinguishing sign

In context, it refers to something that would allow people to recognize or identify someone.

So the exact English word depends on the situation:

• uniform badge
• official insignia
• identifying label
• distinguishing feature

De ahí que is a set expression meaning:

• hence
• therefore
• that is why
• which is why
• from that comes the fact that...

It links the first idea to a consequence or conclusion.

So:

• Faltaba el distintivo, de ahí que no pudieran identificarlo.
• The badge was missing, which is why they couldn’t identify him/it.

It is a fairly formal or written-sounding connector.

Because de ahí que is one of those expressions that normally triggers the subjunctive.

After de ahí que, Spanish presents the second clause as a consequence, inference, or result derived from the first idea. That is why you get:

• de ahí que no pudieran...

not:

• de ahí que no podían...

So this is a pattern worth learning as a chunk:

• de ahí que + subjunctive

Because the first part of the sentence is in the past:

• Faltaba...

So the consequence is also placed in the past, and Spanish uses the imperfect subjunctive:

• de ahí que no pudieran identificarlo

If the main idea were in the present, you would normally expect the present subjunctive:

• Falta el distintivo, de ahí que no puedan identificarlo.

So this is a matter of sequence of tenses.

Because after de ahí que, Spanish requires the subjunctive, not the indicative.

So:

• no pudieran = correct after de ahí que
• no podían = not correct in this structure

However, no podían identificarlo would be fine in a different sentence without de ahí que:

• Faltaba el distintivo y no podían identificarlo.

That version is more direct and less formal. The original sentence is more elegant and written in style.

Yes. Pudieran and pudiesen are both valid forms of the imperfect subjunctive.

So these are both correct:

• de ahí que no pudieran identificarlo
• de ahí que no pudiesen identificarlo

In modern usage, -ra forms such as pudieran are generally more common.

It breaks down like this:

• identificar = to identify
• lo = him / it

So identificarlo means:

• to identify him
• to identify it

The exact translation depends on what lo refers to in the wider context.

Because in Spanish, object pronouns can attach to an infinitive.

So:

• identificarlo = to identify him/it

With a verb phrase like poder + infinitive, Spanish often allows two positions for the object pronoun:

• no pudieran identificarlo
• no lo pudieran identificar

Both are correct. The original sentence chooses to attach the pronoun to the infinitive.

The subject is an implied they.

Spanish often leaves subject pronouns unstated when the verb ending already shows the person and number.

So:

• pudieran = they could
• here, with no, it means they could not

The sentence does not need ellos because it is already clear from the verb form.

It can mean either him or it, depending on the context.

• If it refers to a man, then lo = him
• If it refers to a masculine noun or an object/thing, then lo = it

Without more context, both are possible.

Yes, it sounds somewhat formal or written, mainly because of de ahí que.

A more everyday way to express the same idea might be:

• Faltaba el distintivo, por eso no pudieron identificarlo.
• Faltaba el distintivo, así que no pudieron identificarlo.

The original sentence is not unnatural, but it has a more polished, explanatory tone.

The comma separates the first clause from the consequence that follows.

Structure:

• Faltaba el distintivo, = first idea
• de ahí que no pudieran identificarlo. = resulting conclusion

This punctuation helps show that the second part is derived from the first. In writing, that comma is normal and helpful.

A very literal version would be something like:

• The identifying badge was missing, hence they could not identify him/it.

A more natural English rendering would usually be:

• The badge was missing, which is why they couldn’t identify him/it.

The literal version helps you see the structure, while the natural version helps you sound idiomatic in English.