A Mexican man illegally residing in the United States has been sentenced to nine years in federal prison for crimes that led to the deaths of 10 illegal immigrants who were being trafficked in a tractor-trailer last year, the federal agency that investigated the case announced Thursday.

Pedro Silva-Segura pleaded guilty in March to one count of conspiracy to transport illegal aliens resulting in death. He will face deportation proceedings after eight months in prison.

Court documents state Silva-Segura, 47, had been in the country unlawfully and living in Laredo, Texas, was part of a human smuggling network. He housed people who had been recently trafficked into the country in a "stash house," or a place people are stashed before being transported to their final destinations, according to U.S. Immigration and Customs Enforcement.

Five of the illegal immigrants Silva-Segura had held in the stash house were then handed over on July 22 to James Matthew Bradley Jr., a truck driver who was supposed to take them and nearly 200 others in his tractor-trailer to San Antonio.

Shortly after midnight on July 23, San Antonio police responded to a call from the Walmart on Interstate 35 and found the tractor-trailer behind the store. Police found Bradley asleep in the cab and 39 people in the trailer, which did not have a working air-conditioning unit.

Of the 39 people found in the truck, eight were found deceased and two later died from injuries sustained from being in the overheated trailer for a prolonged period. About 20 people were in serious condition, and eight others, who were diagnosed at the scene with heat stroke and dehydration, were taken to local hospitals for treatment. Four of the 39 people were between the ages of 14 and 17 and were not accompanied with a parent or guardian.

Bradley claimed he did not know there were as many as 40 illegal immigrants in the trailer and only made the discovery when he exited the truck to use the restroom.

Walmart surveillance video showed the truck driver getting people out of the truck and exchanging them to vehicles that would pull up. Between 70 and 200 illegal immigrants are believed to have boarded the truck with groups being released at different spots.

Some of the victims later told federal agents how they illegally crossed the Rio Grande River in Texas and were able to enter the country. The individual groups of illegal immigrants were brought together from stash houses in border towns and loaded onto the trailer Sunday.

Bradley was sentenced to life in federal prison without parole for one count of conspiracy to transport aliens resulting in death and one count of transporting aliens resulting in death.

ICE's Homeland Security Investigations, the San Antonio Police Department, San Antonio Fire Department, Bexar County Sheriff's Office, and U.S. Customs and Border Protection’s Border Patrol took part in the initial response and investigation.