Customs and Border Protection (CBP) is warning agents to be on the lookout for members of a notorious Venezuelan prison gang coming across the southern border -- just as the socialist country is refusing to take its citizens back. 

A CBP source provided Fox News with an internal CBP intelligence bulletin revealing tattoos and identifiers for Tren de Aragua, a Venezuelan prison gang. Members of that gang have been entering the U.S. illegally through the southern border.

Fox News reported this week that the brother of the suspect in the killing of Georgia student Laken Riley has ties to the gang. Both the suspect and his brother are Venezuelans who entered the U.S. illegally.

ILLEGAL BROTHER OF LAKEN RILEY MURDER SUSPECT LINKED TO VENEZUELAN CRIME GANG: DOJ

Federal authorities have been warning that the gang, also known as TdA and known for its violent turf wars as it expanded into other countries in South and Central America, is trying to establish itself in the U.S., where police are already linking it to organized crime. The FBI has also warned that the gang could team up with the bloodthirsty MS-13.

Last month two suspects in the assault of two NYPD officers were revealed to be members of TdA.

But CBP and Immigration and Customs Enforcement (ICE) sources have expressed frustration to Fox News that Venezuelan gang members are extremely difficult to deport because Venezuela is currently not taking them back.

Only 834 Venezuelans were deported in FY 2023, according to Immigration and Customs Enforcement (ICE) data, despite there being over 335,000 encounters at the border. The administration had started returning illegal immigrants from Venezuela directly to the socialist dictatorship in October as part of a way to discourage the flow to the border. 

While the administration took heat for the flights from immigration activists, who argued Venezuela was not an appropriate country to return migrants due to its human rights abuses, administration officials told reporters in January that it was looking to increase the number of flights.

One official said that "we do have the intention of ramping up repatriation flights to Venezuela" and that the administration sees it as a "critical part" of the broader immigration strategy.

"It’s an important deterrent," they said, with officials also saying they were pleased that Mexico was also now flying migrants straight to Venezuela.

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In December, the administration had made limited exceptions to sanctions on a Venezuelan airline to help facilitate deportation flights from Canada and Latin America. 

But last month, the Wall Street Journal reported that the Maduro regime has stopped flights of deported migrants from both the U.S. and Mexico after the U.S. reimposed some economic sanctions. The flights ended at the end of January, officials told the outlet, after around 1,800 returns.

Before beginning the flights last year, the administration had  extended deportation protections to nearly 500,000 Venezuelans already in the U.S. in September. Venezuela is also part of a controversial parole program for Cubans, Haitians, Nicaraguans and Venezuelans (CHNV) which allows 30,000 migrants with sponsors to fly into the U.S. each month.

Fox is told that Venezuelans can still be removed to Mexico, but that many then typically re-enter the U.S. illegally as a "gotaway."

Fox News' Michael Ruiz and Aubrie Spady contributed to this report.