Те, кто любят такие истории, часто обсуждают, у кого было самое сильное алиби и самый понятный мотив.

Те means those, and кто means who.

So Те, кто любят такие истории literally means Those, who like such stories, i.e. Those who like such stories.

Russian very often uses this two-part pattern:

• те, кто... = those who...
• тот, кто... = the one who...
• те, которые... is also possible, but те, кто... is very common when talking about people.

So те points to the group, and кто introduces the clause describing that group.

This is a very common learner question.

Grammatically, кто is often treated as singular, so кто любит is absolutely possible and is often felt to be a bit more formal or traditional.

But when кто refers back to a clearly plural word like те, Russian also very often uses a plural verb:

• Те, кто любит...
• Те, кто любят...

Both can be found.

In this sentence, любят agrees with the meaning of те: we are talking about multiple people, so plural agreement sounds natural.

A simple way to remember it:

• кто любит = more strictly grammatical/formal
• те, кто любят = very common because it matches the real plural meaning

Because любить takes the accusative case: you love something.

The base form is:

• такие истории = such stories

Here, истории is plural and inanimate. For inanimate plural nouns, the accusative plural is the same as the nominative plural. So the form stays истории.

And такие matches истории in number and gender:

• такие = plural
• истории = plural

So:

• любят такие истории = like such stories

There are three commas, and each one has a job.

1. Те, кто любят такие истории, ...

The phrase кто любят такие истории is a subordinate clause describing те, so it is set off with commas.

2. ..., часто обсуждают, у кого было...

The part у кого было самое сильное алиби и самый понятный мотив is another subordinate clause, this time an indirect question after обсуждают.

So the commas mark clause boundaries:

• Те, кто любят такие истории, = Those who like such stories
• часто обсуждают, у кого... = often discuss who had...

Literally, у кого было means something like at whom there was.

Russian often expresses possession with this pattern:

• у + genitive + быть

For example:

• У меня есть книга = I have a book
• literally: At me there is a book

In the past tense:

• У него было алиби = He had an alibi

So:

• у кого было...? = who had...?

Here кого is the genitive form of кто, because у requires the genitive.

Could Russian use иметь? Yes, but иметь is often more formal, abstract, or less natural in everyday contexts. For ordinary possession, у кого было is usually the more natural Russian way.

This is a subtle point.

You might expect были, because there are two things:

• алиби
• мотив

But in Russian, in existential/possessive constructions like у кого было..., singular neuter было is very common, especially when the verb comes before the nouns.

So у кого было алиби и мотив is a natural Russian way to say who had an alibi and a motive.

There are two reasons this feels natural here:

1. The whole phrase is treated a bit like a single package of information: had X and Y.
2. The first noun, алиби, is neuter singular, which fits well with было.

You may also encounter были in similar sentences, especially if the speaker wants to emphasize the two items more clearly as separate things. But было is very natural here.

Алиби is an indeclinable noun borrowed from another language. That means it usually keeps the same form in all cases.

So you get:

• алиби
• без алиби
• с алиби

The form stays the same.

Its grammatical gender is usually neuter, which is why the adjective is:

• самое сильное алиби

not:

• самый сильный алиби
• самая сильная алиби

So even though the noun itself does not change, the adjective still shows the gender and case information.

This is the very common Russian way to form the superlative:

• самый + adjective = the most ...
• often translated into English as the ...-est

So:

• самое сильное алиби = the strongest alibi
• самый понятный мотив = the clearest / most understandable motive

The adjective agrees with the noun:

• самое сильное → neuter singular, because алиби is neuter singular
• самый понятный → masculine singular, because мотив is masculine singular

So the endings change to match the nouns.

Because in this construction, the possessed things are named in the nominative:

• у него было алиби
• у неё был мотив

That is how Russian possession with у + genitive + быть works: the possessor goes after у, but the thing possessed is usually in the nominative.

So here:

• у кого было самое сильное алиби
• и самый понятный мотив

Both алиби and мотив are the things that the person had, so they appear in the nominative.

No. It is an indirect question.

Compare:

• Direct question: У кого было самое сильное алиби? = Who had the strongest alibi?

• Indirect question: Они обсуждают, у кого было самое сильное алиби. = They discuss who had the strongest alibi.

So in your sentence, the people are not asking the question directly; the sentence reports what they discuss.

That is why у кого было... comes after обсуждают and is separated by a comma.