The story behind heartbreaking photograph of little girl at the US-Mexico border

It was a photograph that shocked America. A small girl, in a pink top and pink shoes, screaming in distress on a dirt road as her mother is searched by a border agent.

The girl's plight has come to symbolise the controversy over illegal immigrant families being separated at the US-Mexico border.

It is now known that the two-year-old and her mother had spent a month traveling from Honduras before crossing the Rio Grande.

Her picture was taken by John Moore, an award-wining photographer for Getty Images, who was accompanying border patrol agents on the US side of the river.

Mr Moore and the agents heard the sound of rafts splashing and the crack of branches. Then they saw a group of dozens of illegal immigrants, mostly women and children.

As the guards confiscated their belongings the Honduran woman adhered to a request to remove her young daughter's shoe laces.

She then stood up and was patted down. The girl began to scream.

Mr Moore said: "I took only a few photographs and was almost overcome with emotion myself. As a photojournalist it’s my role to keep going, even when it’s hard.

"But as a father, and I have a toddler myself, it was very difficult to see what was happening in front of my lens, and thinking what it would be like for my kids to be separated from me." 

He saw them only briefly before they were placed in a van with other illegal immigrants and taken to a processing centre.

According to the "zero tolerance" policy now in place the child was probably separated from her mother there.

Her name, and her current whereabouts, remain unknown.

Mr Moore said he also saw another mother using the headlights of a patrol vehicle to breastfeed her baby.

A 10-year-old boy was terrified and the photographer tried to calm him by showing him pictures he had taken of the Rio Grande.

Mr Moore said he told the boy: "It will be OK" and then felt guilty, because he did not know what the child's fate would be.