Ella intentó asesinar al hombre.

Yes. In Spanish, subject pronouns are often omitted because the verb ending already shows who the subject is.

• intentó = he/she/it tried
• So Intentó asesinar al hombre already means He/She tried to murder the man

You include ella when you want to:

• emphasize that she did it
• contrast her with someone else
• avoid ambiguity in context

So both are correct:

• Ella intentó asesinar al hombre
• Intentó asesinar al hombre

Intentó is the preterite, which presents the action as a completed event in the past.

• Ella intentó asesinar al hombre = She tried to murder the man
  • a single, completed attempt

Intentaba is the imperfect, which gives more of a background, repeated, or ongoing sense:

• Ella intentaba asesinar al hombre = She was trying to murder the man
  • the attempt was in progress, habitual, or not viewed as a complete event

So intentó is the natural choice for a finished past action.

Because intentar is followed directly by an infinitive in standard Spanish.

• intentar + infinitive
• intentó asesinar

So:

• Ella intentó asesinar al hombre = correct
• Ella intentó de asesinar al hombre = incorrect

This is different from some other expressions, such as:

• trató de asesinar al hombre = She tried to murder the man

So both of these are correct, but they use different patterns:

• intentó asesinar
• trató de asesinar

This is because of the personal a.

In Spanish, when the direct object is a specific person, you usually put a before it.

• asesinar a alguien = to murder someone
• vio al hombre = she saw the man
• conoció a María = he met María

Here, el hombre is a specific person, so Spanish uses a:

• asesinar al hombre

And because a + el contracts to al, you get:

• a + el hombre = al hombre

Because in Spanish, a + el always contracts to al.

• a el hombre → al hombre
• voy al parque
• se lo di al profesor

This contraction is mandatory with el.

But it does not happen with la:

• a la mujer = not contracted

So:

• al hombre
• a la mujer

Both can mean to kill, but asesinar is more specific.

• matar = to kill
  • broader, more general
• asesinar = to murder / assassinate
  • implies unlawful, intentional killing

So:

• Ella intentó matar al hombre = She tried to kill the man
• Ella intentó asesinar al hombre = She tried to murder the man

In your sentence, asesinar is stronger and more precise.

After a conjugated verb like intentó, Spanish often uses an infinitive to express the second action.

Pattern:

• [conjugated verb] + [infinitive]

Here:

• intentó = she tried
• asesinar = to murder

So literally:

• She tried to murder the man

This is very common in Spanish:

• Quiero comer = I want to eat
• Puede venir = He/She can come
• Decidieron salir = They decided to leave

Yes. Asesinar can sometimes be translated as murder or assassinate, depending on context.

But in many ordinary learning contexts, murder is the safest translation.

• asesinar = to murder
• sometimes to assassinate, especially if the victim is a public figure or the killing is politically motivated

Without special context, Ella intentó asesinar al hombre is most naturally understood as:

• She tried to murder the man

Spanish word order is more flexible than English, but some orders sound more natural than others.

Most natural:

• Ella intentó asesinar al hombre
• Intentó asesinar al hombre

Less natural or more marked:

• Intentó ella asesinar al hombre

That version is possible in special contexts, but it sounds unusual and usually adds emphasis or contrast.

For a learner, the safest choices are:

• Ella intentó asesinar al hombre
• Intentó asesinar al hombre

A broad Spain pronunciation would be approximately:

• Ella → EH-ya
• intentó → een-ten-TO
• asesinar → a-se-see-NAR
• al hombre → al OM-bre

A few useful notes:

• ll in modern Spanish from Spain is usually pronounced like y
• the h in hombre is silent
• the stress in intentó is on the last syllable because of the written accent: -tó
• the stress in asesinar is on the last syllable: -nar

The accent mark shows where the stress goes and also distinguishes the form.

• intento = I try / attempt or attempt as a noun
• intentó = he/she tried

So:

• intento → stress earlier
• intentó → stress on the final syllable

The written accent is important because it changes the meaning and the verb form.

Yes. Since al hombre is a masculine singular direct object, you can replace it with lo.

• Ella intentó asesinar al hombre
• Ella lo intentó asesinar

However, that version is not the most natural. In standard Spanish, with intentar + infinitive, speakers often place the object pronoun before the conjugated verb or attach it to the infinitive:

• Ella lo intentó asesinar
• Ella intentó asesinarlo

Of those two, Ella intentó asesinarlo often sounds smoother.

In this sentence, hombre normally means man.

• hombre = man
• marido / esposo = husband

So unless the wider context makes it clear, al hombre should be understood as the man, not her husband.

Grammatically, it is completely natural Spanish. But semantically, it is obviously dramatic because of the meaning.

The structure itself is very normal:

• Ella intentó + infinitive + object

So the grammar is everyday Spanish, even if the situation is not:

• Ella intentó llamar al médico
• Ella intentó abrir la puerta
• Ella intentó asesinar al hombre

Only the verb asesinar makes it sound serious and dramatic.