These four immigrants have something in common. They were recently deported from the United States, and they all had the coronavirus. Even as extreme measures were taken around the world to stop the spread of Covid-19, Immigration and Customs Enforcement, or ICE, continue to detain people in the U.S., move them from state to state and then deport them to other countries. And with them, the virus. The New York Times in collaboration with The Marshall Project has interviewed sick detainees in ICE detention centers over the last four months. We’ve tracked hundreds of domestic and international deportation flights. We’ve spoken with airline staff who operate those flights. And we’ve talked to Covid-positive deportees in Guatemala, El Salvador, India and Haiti. ICE says it has followed C.D.C. guidelines, but our investigation reveals how unsafe conditions and scattershot testing turned ICE into a domestic and global spreader of the coronavirus, and how pressure from the Trump administration forced countries to take in sick deportees despite the risk. To understand how ICE spread the virus, let’s first look at how its detention system works. On any given day, ICE holds tens of thousands of immigrants in a network of private facilities, state prisons and county jails across the U.S. Those detained include everyone from asylum seekers and undocumented immigrants to green card holders with deportable convictions. They’re held in what’s called civil detention while they wait for hearings to determine whether they can remain in the U.S. When detainees lose their immigration cases and are ordered deported, ICE will move them to other detention centers in Louisiana, Texas, Arizona or Florida. From there, immigrants are flown back to their home countries. “Today, I am officially declaring a national emergency.” Although President Trump declared the coronavirus a national emergency on March 13, ICE continued to take immigrants from the community and detain them in facilities where conditions were ripe for the virus to spread. We talked to more than 30 detainees who described centers where social distancing was impossible, and where protective gear was not provided. Yudanys, an immigrant from Cuba, was first detained at the Catahoula Correctional Center in Louisiana while awaiting a decision on his asylum case. When Yudanys was at Catahoula, there was already a confirmed case of the virus — within a month 60 detainees were positive. He tested positive for Covid-19 in May. So far, ICE has confirmed at least 3,000 positive detainees, though testing has been limited. Even as detention centers became hotbeds for the virus, ICE regularly moved detainees around the U.S. We tracked over 750 domestic U.S. flights that carried thousands of detainees to different centers since a national emergency was declared. ICE contracts out these flights to a company called iAero, which operates Swift Air. A Swift flight attendant, who asked to remain anonymous, told us that detainees from different centers are collected and transported together. She and several other airline employees we spoke to said that these flights, which were under the direction of ICE, lacked protective measures for more than a month after the national emergency was declared. Swift Air declined to comment on this story. But ICE confirmed that the airline didn’t have P.P.E. for all of its staff until mid-April. Kanate, a refugee from Kyrgyzstan, is one of those who was moved from place to place. He had been living in the U.S. for 20 years with his wife and two kids when he was detained in 2019. In April, Kanate was moved from the Pike County facility in Pennsylvania to Prairieland, Texas, even though he had been feeling sick. Kanate tested positive for the virus two days after arriving in Texas. ICE said its detention and transfer protocols follow C.D.C. guidelines. While ICE was moving sick detainees around the U.S., it was also deporting them to other countries and exporting the virus with them. We tracked over 200 deportation flights from March 13 through June, and confirmed that hundreds of detainees with Covid-19 were returned to 11 countries — all 11 had placed restrictions on their borders. But there could be many more infected deportees. ICE told us they’ve deported almost 40,000 immigrants from 138 countries since March. Kanate told us that four of his dormmates either tested positive for Covid or had symptoms, but were deported to India anyway. One of them talked to us after he had arrived home. He asked to remain anonymous. He was one of 22 from his flight who tested positive upon arrival. Admild, an immigrant from Haiti, knew he had the virus even before being deported. He tested positive for Covid-19 while detained in Louisiana. He was put in quarantine and deported two weeks later. Admild said he still had symptoms days after landing. Of the hundreds of deportation flights we tracked, Central America was the region most affected. Nearly 60 percent of these flights went to Honduras, Guatemala and El Salvador, all of which had closed their borders as they tried to contain the virus. The Guatemalan government said that 186 deportees had tested positive for Covid-19, so far. We spoke to Lourdes, who was one of 30 passengers on a single flight who tested positive after arriving. Lourdes was hospitalized a few days after landing. El Salvador on the other hand has said that no deportees arrived with the virus. But we spoke to Jorge, who said he started to feel sick while at the Catahoula Correctional Center in Louisiana before he was deported to El Salvador. He said he was one of 32 from his flight who tested positive. Hundreds of deportees are being held in quarantine centers like this one in El Salvador. Sources inside told us at least 10 Covid cases were confirmed in the centers. The Salvadoran government didn’t reply to our request for comment. A key question in all of this is why some countries have continued to take in sick deportees while others have pushed back. The Trump administration has threatened governments with visa sanctions and cuts in humanitarian aid unless they complied with deportations. El Salvador and Honduras have accepted thousands of deportees since March, despite rising rates of Covid there and poor infrastructure to address the pandemic. In April, Trump praised the presidents of both countries for their cooperation, and said he would send ventilators. Guatemala was less compliant, and its president has been blunt. Guatemala asked the U.S. to test migrants, and it temporarily blocked flights. But three days after Trump threatened countries refusing to accept deportees, the flights to Guatemala resumed. ICE confirmed to us that they are only able to administer a sampling of tests before sending immigrants home. Still, the flights go on and sick detainees continue to be deported.