US Customs and Border Protection is seeking to hire private investigators to track down deported immigrants and others who have left the United States, and press them into paying the government money, according to records reviewed by WIRED. The work would cover Mexico, Honduras, and Guatemala, and potentially other countries.

The documents, which cap the so-called Tracing and Payment Recovery Services program at $9 million over the next two years, call for “commercial data verification and physical observation services” to confirm where each person lives. They list photographs of the home as acceptable evidence, along with records such as utility bills, employment files, court documents, or, if the person has died, a death certificate.

The US government will also accept other documentation, so long as it deems it “relevant and credible.” Contractors are also required to deliver a printed flyer, approved by the US government and printed in English and Spanish, listing outstanding fines and fees CBP claims they owe.

As of July, the Department of Homeland Security, CBP’s parent agency, says it has issued more than $84 billion in fines to immigrants it has accused of failing to depart the United States, citing an obscure provision of a 1996 immigration law that sat unused until Donald Trump’s first term. Those fines run against people who are still in the country, at $998 a day for up to five years. Some have reached up to $1.8 million.

Hasan Shafiqullah, the Legal Aid Society’s immigration supervising attorney, says he’s seen some third-party collection agencies add $500,000 in additional administrative fees on top of the US government’s fees.

Legal experts say that the fine notices evade due process and are meant to intimidate people into self-deporting. A recent report from the New York University School of Law’s Immigrant Rights Clinic found that immigrants accused of failing to depart have had their tax returns seized, their wages garnished, and their credit scores ruined after receiving fine notices.

DHS promises that it will forgive failure-to-depart fines if people self-deport using the CBP Home app. The waiver does not include a separate $5,130 fee Congress created last year for people ordered removed in absentia and later arrested by ICE, which the statute bars from waiving or reducing. Someone who left through the app on the promise of a clean slate could still carry that balance.

Alina Das, a law professor and director of NYU’s Immigrant Rights Clinic, says going after people who have left the country with outstanding fines would be a “significant escalation in tactics.”

Charles Moore, a senior attorney at Public Justice, says that the move is “part and parcel” with the Trump administration’s harsh anti-immigration efforts and that it is likely meant to deter people in the countries targeted from wanting to come to the US in the future.

The three debt collection agencies CBP already uses have tried to reach people overseas by letter and phone. As of July, according to the documents, they had not located a single person outside the US. At that time, they say, the government had removed an estimated 66,387 people carrying unpaid CBP fines and penalties.

CBP referred WIRED’s questions to DHS, which did not provide a comment before publication. Mexico’s foreign ministry, Guatemala’s ministry of foreign affairs, and Honduras’s secretariat of foreign affairs did not respond to questions about whether the United States had consulted them or whether they would cooperate with the contractors.

“It makes no sense to go after people here if they don’t have the money,” says Shafiqullah, who is suing the federal government over the fines. “Presumably they don’t have the money there, and they’re not subject to collections. What’s the point of this?”