An MS-13 gang member tried to sneak into the U.S. last week by posing as an Unaccompanied Alien Child (UAC), the Border Patrol said Tuesday, hoping to take advantage of lax American laws that give UAC a quick foothold in the U.S.

Agents said Herbeth Geovani Argueta-Chavez was part of a group of 61 illegal immigrants nabbed as a group in Arizona.

“During initial interviews, he falsely claimed to be an unaccompanied juvenile in hopes of being released,” U.S. Customs and Border Protection said.

Agents continued to press Mr. Argueta-Chavez, who then admitted he was actually an adult, not a minor. He also admitted he was part of MS-13 — though he claimed he was trying to leave the gang.

CBP said Mr. Argueta-Chavez, 18, is from El Salvador.

UAC from El Salvador and other Central American countries are given special treatment compared to Mexicans. Under the law, court decisions and government policy, they are required to be processed and quickly released to social workers, who then try to connect them with sponsors who will take them here in the U.S. — despite their unauthorized status.

They are supposed to show up for deportation cases, but most do not, instead disappearing into the shadows.

UAC have created a new pool of recruits for Mara Salvatrucha-13, the violent gang better known as MS-13, here in the U.S.

But Mr. Argueta-Chavez’s case underscores another danger: gang members attempting to make bogus UAC claims to gain a foothold.