A 12 –year-old boy was tortured and killed along with 11 other Christians weeks ago in Syria, in the latest heart-wrenching account of ISIS’ cruel brutality to trickle out of the black-clad jihadist army’s isolated caliphate.

Word of the murders, which occurred outside of Aleppo, came from a colleague of the boy’s father, a local ministry leader who works with the Christian Aid Mission, a non-profit organization assisting persecuted Christians overseas. ISIS militants cut off the boy’s fingertips, severely beat him and the others before crucifying them, according to the colleague.

“All were badly brutalized and then crucified,” he told the Christian Aid Mission in a conversation recounted to FoxNews.com. “They were left on their crosses for two days. No one was allowed to remove them.”

Eight other ministry team members, including two women who were publicly raped, were beheaded, according to Christian Aid Mission.The eight were offered the choice of converting to Islam, but refused to renounce Christ.They prayed as they knelt before the Islamic State militants, according to the ministry leader, who spoke with relatives and villagers while visiting the site.

"Villagers said some were praying in the name of Jesus, others said some were praying the Lord's Prayer, and others said some of them lifted their heads to commend their spirits to Jesus," the ministry director told Christian Aid Mission. "One of the women looked up and seemed to be almost smiling as she said, 'Jesus!'"

Hundreds of former Muslims in Syrian villages are in danger of being captured and killed by ISIS. According to the Christian Aid Mission, the underground church in the region has developed rapidly since 2014, when ISIS began terrorizing those who refused to pledge allegiance to the caliphate.

“The Islamist extremists were carrying out what they believe is Allah’s proscribed punishment for those that leave Islam or take part in a fight against Islam,” Ryan Mauro, national security analyst for the Clarion Project, told Fox News. “If you want to defeat ISIS and other Islamist extremists, you need to defeat their doctrinal foundation.”

The village where the atrocities took place is currently under the control of ISIS, and according to VanValkenburg the ministry's operatives are in hiding to protect the people who are still living.

“The Syrian Islamists’ jihad doesn’t end with Syrian Christians,” Mauro told FoxNews.com. “They have every intention of spreading that bloodshed around the world, including in America. Syria is the springboard for the jihad in years to come.”

In Syria, the Christian population has fallen nearly two-thirds since civil war started in 2011. In Iraq, the Christian population has fallen from around 1.5 million in 2003 to below 200,000.