Confirmaron la muerte ayer.

Confirmaron is the 3rd person plural preterite of confirmar.

So it means:

• they confirmed
• or sometimes you all confirmed in regions that use ustedes for plural you

In standard Spain Spanish, the most likely reading here is they confirmed.

The preterite is used for a completed action in the past, which fits well with ayer.

Spanish often leaves out subject pronouns when the verb ending already shows the person.

Because confirmaron clearly tells us it is 3rd person plural, Spanish does not need to say ellos.

So:

• Confirmaron la muerte ayer.
• Ellos confirmaron la muerte ayer.

Both are grammatical, but the version without ellos is more natural unless you want emphasis or contrast.

The exact identity of they depends on context: doctors, police, authorities, journalists, etc.

Spanish often uses the definite article where English might not.

Here la muerte refers to a specific death, even if the person is not named in the sentence. It is not talking about death in general as a concept.

So this sounds like:

• the death of a specific person
• usually someone already known from the context

Using muerte without the article here would sound incomplete or unnatural in normal Spanish.

The personal a is mainly used before specific human direct objects.

Examples:

• Vi a María.
• Llamaron al médico.

But la muerte is not a person, so there is no personal a:

• Confirmaron la muerte ayer.

That is completely normal.

Here it means a particular person’s death, not the abstract idea of death.

In news or formal contexts, Spanish often says:

• confirmar la muerte
• investigar la muerte
• anunciar la muerte

Even though the sentence literally contains the death, the intended meaning is usually the death of that person we are talking about.

Yes, ayer can move around. Spanish word order is fairly flexible.

These are all possible:

• Confirmaron la muerte ayer.
• Ayer confirmaron la muerte.
• Confirmaron ayer la muerte.

The most neutral version here is probably Confirmaron la muerte ayer or Ayer confirmaron la muerte.

Putting ayer at the end is very natural and often sounds like simply adding the time information after the main statement.

In Spain Spanish, ayer normally goes with the preterite, not the present perfect.

So:

• Confirmaron la muerte ayer. ✅
• Han confirmado la muerte ayer. ❌ or at least very unnatural in standard Spain usage

In Spain, han confirmado is more natural with time expressions connected to the current time period, such as:

• hoy
• esta mañana
• esta semana
  depending on context

But ayer is a finished past time, so confirmaron is the expected choice.

Yes, it sounds quite formal and especially common in news reporting or official statements.

Spanish news style often uses compact sentences like this:

• Confirmaron la muerte ayer.
• Las autoridades confirmaron la muerte ayer.
• El hospital confirmó la muerte ayer.

In everyday conversation, people might also say something a bit more explicit, depending on context, such as:

• Ayer confirmaron que había muerto.
• Ayer confirmaron su muerte.

But your sentence is perfectly natural, especially in a news-like register.

Yes, if the context makes clear whose death you mean, su muerte is also possible.

Compare:

• Confirmaron la muerte ayer.
  = they confirmed the death; the person is understood from context

• Confirmaron su muerte ayer.
  = they confirmed his/her death yesterday

Using su can be helpful when you want to tie the death more directly to a previously mentioned person. But la muerte is also very common, especially in headlines or reports.

No. Confirmaron is definitely plural.

If it were singular, you would have:

• confirmó = he/she/it confirmed

So:

• Confirmó la muerte ayer. = one person or one institution confirmed it
• Confirmaron la muerte ayer. = more than one person / an unspecified they

It is pronounced with the stress on the second-to-last syllable:

con-fir-MA-ron

That is because Spanish words ending in -n, -s, or a vowel are normally stressed on the penultimate syllable unless there is a written accent mark. Since confirmaron has no written accent, the stress naturally falls on ma.

Grammatically, ayer most directly modifies confirmaron, so the sentence says that the confirmation happened yesterday.

It does not necessarily mean the person died yesterday.

So the sentence means:

• yesterday, they confirmed the death

The actual death could have happened earlier. If you wanted to make it clearer that the death itself happened yesterday, you would normally need a different sentence or more context.