AMNA NAWAZ: Last week, El Salvador's President Nayib Bukele was officially reelected and a landslide win.

Bukele first came into power in 2019.

And for nearly two years, he's overseen a vast and brutal crackdown on gangs, transforming the nation from one of the deadliest in the world to one of the safest in Latin America.

But that peace has come at a cost, thousands of innocent people jailed and critics say an undermined democracy.

I traveled with producer Teresa Cebrian Aranda to two cities north of the capital of San Salvador to file this report.

For two years, Patricia has prayed for her partner's return.

Victor was one of the more than 75,000 people imprisoned in El Salvador's war on gangs.

PATRICIA, El Salvador Resident (through translator): I don't know anything about him.

And that's what hurts the most, because we were a very united family.

AMNA NAWAZ: His absence is felt in every room and at every meal.

In 2022, Victor, whose identity we're protecting, and Patricia's son Rodrigo were arrested, they say without evidence, for alleged gang ties.

Rodrigo was just 16 years old.

What happened in prison?

RODRIGO, Former Detainee (through translator): They beat me.

When I had a stomach ache, a headache, instead of giving me medicine, they would take us all out and beat us.

AMNA NAWAZ: He says about 70 people shared a single cell, but only 10 or so were gang members.

RODRIGO (through translator): They were the ones who controlled the cell.

They would ask for medicine, and they got it.

And to those who weren't anything, they would treat us badly.

Those from the neighboring cell would urinate on us, and the police wouldn't say anything.

AMNA NAWAZ: His stepfather, Victor, remains in prison.

Police said he had a criminal record for petty crime decades ago, but Patricia denies any gang ties.

She showed us documents she's filed for his release, dismissed by the court.

Patricia has been gathering as many character testimonies, letters of recommendation from her church, from his employer, where he worked for 22 years.

She's been submitting all of this to the courts, but so far they have made no difference.

Victor was swept up as part of president Nayib Bukele crackdown on the gangs that have terrorized El Salvador.

For more than two decades, warring factions of the MS-13 and 18th Street gangs killed and extorted civilians with impunity, turning El Salvador into the murder capital of the world.

Nelson Rauda Zablah is the digital editor of El Faro, an acclaimed national investigative.

NELSON RAUDA ZABLAH, Digital Editor, El Faro: For the people who live under gang-controlled communities, for the people who use public transportation, for the people who maybe just was in the wrong place in the wrong time, it was unbearable.

AMNA NAWAZ: Nayib Bukele swept into power in 2019.

In his first year in office, the murder rate dropped by half.

But in March of 2022, a gang killing spree, 87 people dead in one weekend.

Bukele responded with an iron fist.

He deployed the military, declared a state of exception, limiting some rights, and empowered police to arrest without a warrant.

This police officer, whose identity were protecting, said officers were issued arrest quotas, at one point five arrests a day.

POLICE OFFICER (through translator): Given that we had arrest goals, when we no longer found gang members, we began arresting people who had nothing to do with gangs.

AMNA NAWAZ: And what happens to those people after you arrest them?

POLICE OFFICER (through translator): They are detained, and we charge them with the crime of unlawful association.

A lot of innocent people are still in prison, and we have participated in that, because we thought they'd be released soon.

And that has not been the case.

NOAH BULLOCK, Executive Director, Cristosal: And the majority of them, upon being detained, basically disappeared into the prison system.

Family members don't know if they're alive, don't know where they are, aren't able to contact them.

AMNA NAWAZ: Noah Bullock is the executive director of Cristosal, a human rights group based in El Salvador.

They have documented thousands of arbitrary arrests during that state of exception, as well as abuse and death inside prisons.

We spoke during his recent visit to Washington.

For all those people who are detained, what's the recourse like for their families or loved ones?

What can people do?

NOAH BULLOCK: Very little.

What is lost in terms of rights and freedoms for Salvadorans in the state of exception is the guarantee to be able to have a fair trial, to be able to defend themselves against these types of charges.

And for many families, it becomes a reign of terror.

That's what the Catholic bishop in El Salvador called it.

AMNA NAWAZ: In San Martin, an hour outside of San Salvador, Mauricio Vilanova tours us around streets once too dangerous to walk.

He's mayor of neighboring San Jose Guayabal.

MAURICIO VILANOVA, Mayor of San Jose Guayabal, El Salvador (through translator): Dead people, extortion, territories controlled by the gangs.

There was no freedom here, not even for residents.

There was a state within a state.

AMNA NAWAZ: What used to be one of the deadliest areas in the country is now safe enough for children to play.

Just to give you a sense of how dramatically life has changed here, people tell us this road used to be essentially a dividing line.

That community was controlled by the MS-13 gang, this community controlled by the 18th Street gang, and, for some, crossing would mean a death sentence.

Vilanova, who some gang leader still want dead, carries a weapon wherever he goes.

But Bukele's policies, he says, have been transformative.

What about the innocent people who are rounded up and held as part of the state of exception, but are completely innocent?

MAURICIO VILANOVA (through translator): Yes, of those detained here are some people who have been released already.

I have faith in God that those who do not fear and will be judged will be free.

AMNA NAWAZ: The government has so far released 7,000 people, but thousands of families say their innocent loved ones are still held.

Maribel Amaya (ph) last saw her son Jorge Luis a few blocks away from her vegetable stand outside of San Salvador.

Her son had no criminal record.

She says he was arrested to fill a police quota.

MARIBEL AMAYA, Mother (through translator): Another mother who was there and whose son was also arrested that day, before she left the police station, she heard police saying, "I need one more."

And that one more was my son.

AMNA NAWAZ: No visitors are allowed at the Mariona prison, where he's held.

But once a month, Maribel makes the trip to drop off food and clothes he won't get inside.

Each package costs almost $100, about a third of her monthly income.

After a friend sent her this photo of a much thinner Jorge Luis in a hospital being treated for malnutrition, she says she will spare no expense.

MARIBEL (through translator): I can wait, but my son cannot anymore.

I don't understand how they can sleep at night with all these injustices they are creating.

I will never stay silent.

Why?

Because I don't want a funeral home to call me one day and tell me that my son is in a morgue.

AMNA NAWAZ: Of the tens of thousands arrested, the majority have not yet faced trial.

A new law allows for mass trials of up to 900 people at a time.

Gustavo Villatoro is El Salvador's minister of justice and public security.

GUSTAVO VILLATORO, El Salvador Minister of Justice and Public Security (through translator): We do guarantee that all these people will face justice, a judge decision on whether they are guilty or innocent.

We are now in the transitional process, and we will soon begin the accusations.

AMNA NAWAZ: Critics say President Bukele's grip on power has only tightened.

In his first term, Bukele removed the attorney general and replaced top judges on the Supreme Court, who then reinterpreted the Constitution, allowing Bukele to run for a second consecutive term.

The government has also targeted critics, including human rights groups and journalists.

NELSON RAUDA ZABLAH: We have been severely attacked.

We have gotten death threats.

The Inter-American Commission on Human Rights thinks that our lives and our jobs are in danger in El Salvador.

AMNA NAWAZ: But Salvadorans, now free of gang control support, Bukele.

Just last week, he won reelection with nearly 83 percent of the vote.

NAYIB BUKELE, President of El Salvador (through translator): We literally went from being the most dangerous country in the world to being the most secure in all the Western Hemisphere.

NOAH BULLOCK: The security results are felt by everyone.

And I think the challenge is helping people who have been subjected to the terror of gangs for decades process what might have been lost in exchange for that security.

AMNA NAWAZ: What does a second term under Bukele mean for democracy in El Salvador?

NELSON RAUDA ZABLAH: The end of it.

What would you call a system where one person calls all the shots, where there's no separation of power?

After a fair report, you would hard -- you would find it really hard to call it a democracy.

AMNA NAWAZ: Today, the streets of El Salvador are largely quiet and peaceful, but many worry peace at this cost may not prevail for long.