Camilo Perez-Bustillo, a professor of human rights in Mexico City, spoke to Al Jazeera on the dangers migrants face as they make the journey through Central America to the United States.

Perez-Bustillo said decriminalising illegal immigration would help stop the flow of drugs. 

"Just as we need to decriminalise drug trafficking, we need to decriminalise illegal immigration, too," he said. "Those who can cross border without detection can also pass drugs without detection," he said.

Camilo Perez-Bustillo said US economic policies have worsened the situation.

"Since the North America Free Trade Association was launched 17 years ago, the number of undocumented immigrant labours to the US has spiked," he said.