AUSTIN – U.S. Rep. Joaquin Castro of Texas says in a letter to the secretaries of Homeland Security and Health and Human Services that he's heard reports that at least two asylum-seeking immigrants have committed suicide while in federal custody.

He also expressed continued frustration about the agencies' lack of transparency concerning family reunification efforts.

"Specific questions included, what tracking system is in place to locate children in the government's custody and what information is provided to parents to keep them apprised of their children's whereabouts?" Castro, a San Antonio Democrat, said in the letter drafted Thursday to Homeland Security Secretary Kirstjen Nielsen and HHS Secretary Alex Azar. "We still have not received a response."

Neither agency immediately responded to request for comment by the USA TODAY Network.

636657179653104626-Immigration-Brownsville.jpg
Two women seeking asylum on Wednesday, June 27, 2018, wait on the Mexico side of the border near Brownsville, Texas.
Courtney Sacco/Caller-Times

In a separate statement, Castro and four other congressional Democrats called on the U.S. State Department to provide details on whether the Trump administration has failed to comply with the court-ordered reunification of some children under age 5 because their parents have been deported without them.

“Now we know some of the parents subjected to this inhumane practice are indeed back in their home countries," Castro in the statement cosigned by U.S. Reps. Eliot Engel of New York, Norma Torres of California, Adriano Espaillat of New York and Albio Sires of New Jersey.

636280591634861684-100477802-CastroVisit05.jpg
U.S. Rep. Joaquin Castro talks about a possible run against U.S. Sen. Ted Cruz during a meet-and-greet Monday, April 17, 2017, at the Corpus Christi Regional Transportation Authority in Corpus Christi.
Gabe Hernandez/Caller-Times

"So it’s time for the State Department to step up. Secretary (Mike) Pompeo should instruct our embassies to do whatever it takes to find these parents and get them back with their children."

U.S. District Judge Dana Sabraw has ordered the Trump administration to end family separations as part of its zero tolerance policy on illegal immigration. Her order instructs federal authorities to reunite nearly 2,600 children and their parents by July 26.

Reunifications for children under age 5 began earlier this month.

More: Looming debate over DACA program spurs federal lawsuit

More: Agents raid Texas 'stash house' and find 62 undocumented immigrants, says border patrol

More: Family helps rescue stranded Cuban migrants floating on truck tire off coast of Florida Keys