Nigerian President Muhammadu Buhari and other authorities are considering offering Boko Haram prisoners amnesty in exchange for the more than 200 Chibok girls the radical Islamic group kidnapped 16 months ago.

“The few (prisoners) we are holding, we are trying to see whether we can negotiate with them for the release of the Chibok girls,” he stated. “If the Boko Haram leadership eventually agrees to turn over the Chibok girls to us–the complete number–then we may decide to give them (the prisoners) amnesty.”

In April 2014, Boko Haram invaded Chibok and kidnapped hundreds of young Christian girls. The group received massive international criticism, including the hashtag #BringBackOurGirls on social media. First Lady Michelle Obama posted a picture of herself holding a sign with the hashtag. At least 57 girls escaped, but 219 are still missing.

In July, Boko Haram announced they are willing to swap over 200 of the Chibok schoolgirls kidnapped in April 2014 for 16 terrorists who are being held by the government.

An anonymous human rights activist told the Associated Press that the group made the same offer last year when Goodluck Jonathan was president. That deal fell through due to last-minute problems. The activist claimed the swap was “stymied by the Department for State Service intelligence agency,” and “the agency said it was holding only four of the militants sought by Boko Haram.”

But earlier this month, Buhari told BBC Hausa that he believes Boko Haram forced the majority of the Chibok girls into marriages.

“They [Boko Haram insurgents] have scattered them, and [they] are being guarded at dispersed locations,” he said. “Most of the girls are Christians and were forced to embrace Islam. The sect’s cruel leaders have married some of the girls, obviously against their wish. Others have been left to practice their religion but their condition could hardly be ascertained.”

Since the incident, many who escaped or survived Boko Haram attacks claim they witnessed the Chibok girls with militants. The most recent accounts state the terrorists brainwashed the girls.

The terrorists indoctrinated the young girls, who now carry “out punishments on behalf of the militants.” Miriam, 17, escaped the group, but like Tabitha, was forced into marriage and is also expecting a child. Fighters slit men’s throats in front of Miriam and other girls to show them what would happen if any refused to marry the terrorists. A few Chibok girls resided at the camp. Miriam spoke with them, even though militants housed them in a different building. The BBC reports:

“They told us: ‘You women should learn from your husbands because they are giving their blood for the cause. We must also go to war for Allah.’”

She said the girls had been “brainwashed” and that she had witnessed some of them kill several men in her village.

“They were Christian men. They [the Boko Haram fighters] forced the Christians to lie down. Then the girls cut their throats.”

Anna, 60, fled from Boko Haram, but also lived with the Chibok girls:

She said she saw some of the Chibok schoolgirls just before she fled the forest.

“They had guns,” she said.

When pressed on how she could be sure that it was the Chibok schoolgirls that she’d seen, Anna said: “They [Boko Haram] didn’t hide them. They told us: ‘These are your teachers from Chibok.’”

“They shared the girls out as teachers to teach different groups of women and girls to recite the Koran,” Anna recalled.

“Young girls who couldn’t recite were being flogged by the Chibok girls.”

Like Miriam, Anna also said she had seen some of the Chibok schoolgirls commit murder.

“People were tied and laid down and the girls took it from there. … The Chibok girls slit their throats,” said Anna.