It was November 2019, just days after Evo Morales had abandoned Bolivia’s presidency and fled into exile, and the country’s newly installed interior minister was making no effort to hide his glee.

“Any terrorist should spend the rest of their life in prison,” Arturo Murillo gloated during an interview in his recently occupied chambers, vowing to put the runaway leftist behind bars for the next 30 years.

“It’s not about whether you’re an ex-president,” the pugnacious hotelier-turned-politician insisted. “In fact, it’s even worse when it’s an ex-president. An ex-president should be sentenced twice over because people trust in their president.”

This week, an ex-president was indeed jailed in Bolivia – but not Morales. Instead, it was Murillo’s former boss, Jeanine Áñez, who found herself languishing in a La Paz prison cell after being seized by security forces early on Saturday. “We’re seeking a 30-year sentence,” Bolivia’s new justice minister, Iván Lima, announced, as Áñez was accused of terrorism and sedition – the very same charges Murillo had levelled at Morales.

The imprisonment of Áñez, a Bible-bashing conservative who became interim leader after Morales fled under pressure from the military, was met with jubilation by some. Many on Latin America’s left celebrated the downfall of a politician they allege played a central role in the coup they say forced Bolivia’s first indigenous president from power.

“Coup-mongers belong in jail!” tweeted the Brazilian leftist Guilherme Boulos as news that Áñez had been found cowering in a storage bed reached Bolivia’s neighbour. She will spend the next four months in pre-trial detention, including 15 days isolated from other prisoners as a precaution against Covid-19.

Others, however, described the arrest as an alarming development in an already profoundly divided country which the new leftwing president, Luis Arce, had pledged to unify after Morales’s Movement for Socialism (Mas) party reclaimed power last October. This week tens of thousands of demonstrators hit the streets of cities including La Paz, Cochabamba, Sucre and Santa Cruz to protest against Áñez’s treatment, suggesting such healing would have to wait.

“We are in a cycle of retribution,” warned Jim Shultz, the founder of the Bolivia-focused Democracy Center. “If you’re in a government and the government changes at this point, you can pretty much count on them coming after you … [This] feels less like a legal process and more like they are taking turns trying to destroy one another.”

Few doubt Áñez has serious questions to answer over the persecution of political rivals and human rights abuses that took place during her year-long stint as interim president, which began after Morales’s escape to Mexico and ended last November after the sensational electoral fightback that returned his party to power and allowed him to return home.

“While she was president, at least 20 Mas supporters were killed in two massacres,” said José Miguel Vivanco, the Americas director for Human Rights Watch. “Witnesses told us that state forces opened fire against protesters.”

Shultz remembered how after taking power in November 2019 Áñez had moved to shield from prosecution members of the armed forces who were attempting to quell the unrest sweeping Bolivia. Days later, on 19 November, troops were accused of opening fire on unarmed Morales supporters in the city of El Alto, killing at least eight.

Shultz said: “When you have a president who says to the army and the police in advance of an action: ‘Whatever you do, you will not be prosecuted’, that message is about as clear as you can get: ‘Kill who you want to kill’. That is what she should be prosecuted for.”

That may well happen. On Monday, Arce’s justice minister announced that an investigation into those “bloody massacres” would be complete by June and said the mothers of the victims were crying out for justice.

For now, however, the charges brought against Áñez relate not to those shootings, but to claims the former senator was involved in plotting the rightwing coup that Bolivia’s current government claims brought her to power. Vivanco said his group had reviewed Áñez’s charge-sheet and found no evidence of crimes. Rather, what appeared to be unfolding was “the abuse of the justice system against political opponents”.

Shultz said he also found claims Áñez had masterminded Morales’s overthrow “a stretch”. Several Mas politicians had been constitutionally in line to fill the presidency ahead of Áñez after his resignation but declined to do so, he noted. “She just caught the ball,” Shultz said of Áñez. “She didn’t throw it.”

Áñez, who claims she is the victim of a campaign of political persecution, is not the only member of her administration being targeted by Bolivia’s new government. Two former cabinet members – the former justice minister Álvaro Coímbra and former energy minister Álvaro Rodrigo Guzmán – have also been detained. Her former communications minister, Roxana Lizárraga, is seeking asylum in Peru. On Monday the former army commander, Gen Jorge Pastor Mendieta Ferrufino, surrendered himself to authorities over the same investigation.

Meanwhile Murillo, who is 57, slipped out of the country on the eve of last year’s election, reportedly passing through São Paulo and Panama City en route to the United States. A warrant has also been issued for his arrest.