Jeanine Añez, the former president of Bolivia, was sentenced to 10 years in prison on Friday following accusations that she illegally took over the presidency after the resignation of her predecessor, Evo Morales.

The trial, the latest chapter in Bolivia’s long-running political turmoil, has raised concerns that the country’s leaders are using the courts to target political adversaries, and that the sentencing represents a larger democratic crisis in the small South American country and across the region.

“Democracy is in question, not just in Bolivia, but all of Latin America,” said Gonzalo Mendieta, a lawyer and political analyst based in Bolivia’s seat of government, La Paz.

Ms. Añez was arrested on March 13, 2021, in her hometown, Trinidad, and taken to La Paz after a warrant was issued accusing her of terrorism and sedition. She was also charged with several other offenses, and was held in prison for nearly 15 months awaiting trial.

She was sentenced on Friday by the Tribunal Primero de Sentencia de La Paz, on the charges of breaching her duties and enacting resolutions against Bolivia’s Constitution.

Luis Guillén, Ms. Añez’s lawyer, told The New York Times that he believed the court’s decision was politically motivated and that Bolivia’s current government, led by a socialist ally of Mr. Morales, broke the law in their treatment of Ms. Añez during her detention.

We will “exhaust resources within the country and then appeal to international organizations,” Mr. Guillén said.

Iván Lima, Bolivia’s justice minister, denied the accusations, saying there was “no evidence” to support them. “We are a government that respects the rules of due process, and that extends democratic rule to all political actors,” Mr. Lima said in an interview.

Once a little-known conservative senator, Ms. Añez rose to the forefront of Bolivia’s political scene in November 2019, when Mr. Morales, Bolivia’s longtime president, a socialist and the country’s first Indigenous leader, lost his grip on power and fled into exile in Argentina amid violent protests set off by his disputed election.

Ms. Añez stepped forward, promising to be only a caretaker interim president and to hold new elections in which she would not run. But almost immediately, she started to reshape Bolivia’s foreign policy. A conservative Christian, she introduced religious symbols into secular state procedures and started a campaign against the leftist supporters of Mr. Morales, who during his 14 years in office had stressed the importance of Indigenous culture.

Her government then charged Mr. Morales with sedition and terrorism, though international human rights groups said evidence to substantiate those charges was lacking and called the case against him politically motivated.

Ms. Añez’s defense team has insisted that in 2019 she had to step in to fill a power vacuum, but Mr. Morales’s supporters called the ouster a “coup.”

In closing testimony on Friday Ms. Añez echoed their arguments, telling judges that she was innocent and that her rise to power was “a consequence of all that happened” two years ago.

“I didn’t move a finger to reach the presidency,” Ms. Añez said.

It did not take long for Ms. Añez, 54, to become deeply unpopular with the Bolivian public, for reasons that ranged from purported human rights violations to her antagonism of Mr. Morales’s Movement to Socialism party, which remains Bolivia’s largest, and perhaps most significantly, her handling of the coronavirus pandemic and the economic disruption that followed.

Ms. Añez abandoned her campaign for Bolivia’s presidency about a month before the Oct. 18, 2020, election, when voters chose the Morales-backed socialist Luis Arce.

She has denied the allegations against her and said she was a victim of “political persecution.”

As prosecutors presented final arguments inside the court on Wednesday, a group of anti-Añez protesters gathered outside, many of whom said they had been oppressed during her government. They called for the ex-leader to receive the maximum sentence, 15 years, screaming “no negotiation with spilled blood.”

The sentencing represents a victory for Mr. Arce’s government and the Movement Toward Socialism party, reinforcing its long-held narrative that Ms. Añez’s rise to power was a coup.

But the decision also has spurred concerns about the independence of Bolivia’s justice system, which Cesar Muñoz, a senior researcher for Human Rights Watch, said has been harnessed by previous governments on both ends of the political spectrum to seek “revenge” on their political opponents.

“We worry about what this means for the impartiality of the justice system,” Mr. Muñoz said. “Those in power have used the justice system for their own political purposes.”

Mr. Morales’s government faced allegations of political persecution of journalists and opposition politicians, as well as the manipulation of the judicial system for political ends.

Human Rights Watch said the government of Ms. Añez “publicly pressured prosecutors and judges to act to further its interests,” which the group said led to criminal investigations of more than 100 people connected to the Morales government over accusations of crimes of sedition or terrorism.

Under Mr. Arce’s government, Ms. Añez now faces the same charges of terrorism for crimes she is said to have committed before her presidency — and for which Mr. Muñoz said there is equally little evidence — as well as accusations of genocide from her time in office.

The State Department, alongside other observers like the European Union, has expressed worries about “growing signs of anti-democratic behavior and the politicization of the legal system in Bolivia.”

The ruling also comes as several other Latin American leaders have shown authoritarian tendencies.

Most notably, in El Salvador more than 36,000 people were arrested after the country’s Parliament gave President Nayib Bukele the power to suspend some civil liberties to crack down on gang violence. The Brookings Institution has also noted “democratic erosion” in Haiti, Honduras, Guatemala, Paraguay, Nicaragua and the Dominican Republic.

“When you examine the region, it looks incredibly tumultuous,” Mr. Mendieta, the lawyer and political analyst in La Paz, said.