– A Honduran migrant separated from his wife and child under the Trump administration's new "zero tolerance" policy was found dead in his Texas jail cell last month.

Marco Antonio Munoz, 39, crossed into the U.S. from Mexico with his wife and 3-year-old son on May 12 near Granjeno, a U.S. town where Central American families seeking asylum often turn themselves in to Border Patrol agents. Munoz and his family were detained and taken with others to a processing center in nearby McAllen.

The death is the latest incident to cast a harsh spotlight on the zero tolerance policy, which advocates for immigrants have denounced as inhumane, and on the processing center, which a U.S. senator recently likened to a dog kennel.

After being told his family would be separated, Munoz became upset and struggled with agents, according to an agent who spoke on condition of anonymity. Munoz was taken to a jail where, authorities say, he committed suicide.

In recent months, Border Patrol staff have become concerned about conditions at the processing center as the number of families being held increases, the agent said. The facility, a converted warehouse, opened as a temporary processing and holding area in 2015 after an influx of Central American families strained the jail-like concrete holding cells at the Border Patrol station in nearby McAllen.

The processing center is sectioned off by pieces of cyclone fence attached in some places with bolts and zip ties. Men are separated from women and children when they arrive, and unaccompanied children are held separately. There are benches to sit on, televisions suspended above and portable toilets.

"It's like a kennel," the agent said. "It's not a jail facility."

Under the zero tolerance policy, many migrants are now charged in federal criminal court with illegally entering the country, a misdemeanor, before their cases proceed to administrative immigration court. Adults are held by Border Patrol and transferred to federal detention, and their children are placed in federal shelters or foster care.

As a result, more people have been held at the McAllen processing center longer than in the past, including more men, the agent said. There have been outbreaks of chicken pox and scabies, and agents frequently get sick.

"It's one thing when you have families with kids; it's another when you have grown men with criminal records and ill intent," the agent said. "It's super-crowded. It gets to the point where we have to stop sending people there. There's days where there's over 1,000 people there. They have to send them to other stations until we can whittle them down."

On Wednesday, a federal judge in California allowed a class-action lawsuit to proceed against the Border Patrol, filed by the American Civil Liberties Union on behalf of parents separated from their children. The United Nations human rights office and doctors' and immigration lawyers' organizations have condemned the policy, as did Sen. Jeff Merkley, D-Ore., after visiting the McAllen processing center on June 3.

Merkley also tried to visit a federal shelter for migrant children in nearby Brownsville but was turned away.

He described the Border Patrol facility as a crowded "Walmart warehouse children's prison" with "dog kennel-style cages." "The only thing they had was their clothing and these space blankets. There was no padding on the floor. Some were sitting, some were standing," Merkley said at a briefing after his visit.

He described agents "ripping children out of the parents' arms to inflict harm on the child and influence the parents," adding, "there is no need to separate them from their parents when they're awaiting asylum."