If you thought the age of Christian missionaries traveling the world to spread the word of God and evangelize locals was over, think again—they’ve just gotten sneakier.

A recent investigation by The Guardian and the Brazilian newspaper O Globo reveals that missionaries have left solar-powered audio devices in Brazil’s Javari valley, near the Peruvian border, in an attempt to evangelize isolated or recently contacted Indigenous Amazonian people. The devices play biblical readings in Portuguese and Spanish.

For example, a device identified by The Guardian announces, “Let’s see what Paul says as he considers his own life in Philippians chapter 3, verse 4: ‘If someone else thinks they have reasons to put confidence in the flesh, I have more.’”

The Javari Valley Indigenous Territory has the highest concentration of uncontacted human groups in the world. To protect the indigenous tribes, Brazil’s National Foundation for the Indian (FUNAI) made it illegal to enter Javari Valley in 1987. Nevertheless, locals have reported up to seven audio devices, though the investigation secured photo and video evidence of just one—a yellow and gray phone-sized gadget that materialized in a Korubo village and plays audios spoken by an American Baptist.

The Korubo are members of a recently contacted group of indigenous people known for their war clubs. According to the investigation, the device is now in the hands of a Korubo woman named Mayá.

The device is reportedly called “Messenger,” and the Baptist organization In Touch Ministries donates them to “unreached” people around the world, as reported by the investigation. In fact, their website clearly features what seems to be a version of the device, along with a whole host of similar gadgets.

“What began with a solar-powered audio player containing the Bible and Dr. Stanley’s messages is now much more than a device,” reads the website. “Wherever we go, we look for the right solution at the right time—whether it’s one of our proprietary devices or another tool—to make sure the message of salvation in Jesus Christ is accessible to those who have never heard.”

In Touch Ministries’ chief operating officer Seth Grey, however, told The Guardian that while he knew of missionaries from other organizations who bring Messengers to regions where it is illegal to do so, “we [In Touch staff] don’t go anywhere we’re not allowed.”

In case anyone forgot since the last time we reported on Westerners trying to contact isolated tribal people, such contact could transmit devastating diseases to communities with little to no immunity to them. Of course, this risk is higher in the case of direct physical contact, as opposed to leaving gadgets outdoors, but it’s still in violation of Brazil’s public policy for the protection of isolated indigenous peoples of not establishing contact.