Everyone had an idea about how the 12-year-old girl should pose in a G-string bikini as they assembled in an Airbnb rental home in a small Louisiana town.

The photographer was new to the business of shooting child influencers, so he welcomed suggestions, he later explained in an interview.

The girl’s mother, swiping through images of women from men's magazines on her phone, recommended that she stand with one leg raised provocatively on a bed, he recalled. The girl, he said, proposed imitating a scene from an erotic film she had watched — she would lie on her back with her hands grasping for the bedposts.

In the end, several shots positioned her “head on a pillow and her buttocks raised in the air,” and in one, the camera focused on her “barely covered” genitals. That was the description in court documents, written by federal authorities who charged the photographer and mother with crimes related to child sexual abuse material.

“We just provided what we knew that men wanted to purchase,” the photographer, Grant Durtschi, said by telephone from a jail outside Baton Rouge.

For the past year, The New York Times has been investigating how a drive for online fame has created a marketplace on Instagram of girl influencers who are managed by their parents — Instagram does not allow children under 13 to have their own accounts — and frequently draw an audience of men.