Detainees have vanished from the Immigration and Customs Enforcement (ICE) online database, with families and lawyers unable to track them.

“When searching for people detained there, the ICE locator now says, ‘Call the Florida Department of Corrections for details,’” said Luis Sorto of Sanctuary of the South, which has taken part in litigation over access to legal representation at the facility.

Many detainees, including plaintiffs in a recent lawsuit challenging Florida’s authority to detain people at the site, were reportedly transferred elsewhere after the case was filed in August.

The American Civil Liberties Union (ACLU) described the camp as a “black hole” where detainees are “missing”, with families and lawyers left in the dark.

Eunice Cho, senior staff attorney at the ACLU’s National Prison Project, said ICE’s “persistent refusal” to promptly update detainee locations undermined due process and “is yet another hallmark of the detention system’s cruelty”.

The Miami Herald reported that as of late August, around 800 detainees no longer appeared in ICE’s online system, while a further 450 were listed only with the message: “Call ICE for details.”

The centre has faced legal challenges since its establishment in July on a former Everglades airstrip. A judge ordered it dismantled in August following environmental lawsuits, but the ruling was stayed on appeal.

State officials nevertheless indicated the facility would soon be emptied, with detainees transferred to other sites in Florida and beyond — some already criticised for poor conditions. Governor Ron DeSantis said in late July that about 100 people had been deported.

Confusion persists over how many have been deported or moved. Some detainees told reporters they were pressured into agreeing to deportation. One Miami immigration lawyer, Alex Solomiany, said he discovered his client had been accidentally deported to Guatemala while he was seeking him at another detention centre.

The Department of Homeland Security said “the number of detainees at Alligator Alcatraz fluctuates constantly as they are deported and transferred to ICE detention centers for further removal proceedings”.