SAN ANTONIO (AP) — One of six men charged in Texas over 53 migrants who died last year in a sweltering tractor-trailer has pleaded guilty for his role in the nation’s deadliest human smuggling attempt from Mexico, federal prosecutors said Wednesday.

Christian Martinez, 29, is the first conviction for the U.S. government over the tragedy in San Antonio, where the truck was found on a remote back road in June 2022. The dead included eight children who were riding inside the trailer that had no air conditioning in the sweltering Texas heat.

Martinez pleaded guilty to four smuggling-related charges and faces up to life in prison. Court records show his sentencing is set for Jan. 4.

David Shearer, an attorney for Martinez, declined comment.

Prosecutors said Martinez, who lived in suburban Houston, took the driver of the trailer to San Antonio to pick up the vehicle before it made its way to the U.S. border city of Laredo. Once there, Homero Zamorano Jr. allegedly loaded the migrants into the trailer and made his way back north while Martinez and four other men passed messages and made each other aware of the trailer’s progress.

Zamorano and the other defendants are still awaiting trial. Zamorano has pleaded not guilty.

An indictment unsealed in June alleged that the men worked with human smuggling operations in Guatemala, Honduras and Mexico. They allegedly shared routes, guides, stash houses, trucks and trailers, some of which were stored at a private parking lot in San Antonio.

The truck had been packed with 67 people, and the dead included 27 from Mexico, 14 from Honduras, seven from Guatemala and two from El Salvador, authorities in Mexico said.

Migrants paid the organization up to $15,000 each to be taken across the U.S. border. The fee would cover up to three attempts to get into the country, according to the indictment.