GUILLERMO ARIAS/AFP via Getty Migrants walk towards El Chaparral port of entry in Tijuana, Mexico, at the border with the United States on June 21, 2018.
Lawyers said this week they still haven’t been able to locate the parents of 545 migrant children separated at the U.S.-Mexico border under the Trump administration's controversial "zero tolerance" policy.
NBC News first reported on the update Tuesday, citing a federal court filing by the American Civil Liberties Union and the Justice Department.
The steering committee working to reunite the families — including ACLU attorneys and other organizations, who were tasked by a judge to work with the government on reunification — said in its latest update that they believe about two-thirds of the parents have since been sent out of the country.
In the filing, reviewed by PEOPLE, the committee says they’ve tried to reach out to parents via phone calls, letters and on-the-ground efforts across Mexico and Central America.
However, the novel coronavirus (COVID-19) pandemic has “hampered” the group's on-the-ground efforts to track down many of the parents, the filing states.
Lawyers from the ACLU and law firms working pro-bono in coordination with the government — following a 2018 court order — have been searching for the parents of migrant children separated by the Trump administration at the southern border since the widespread family detentions drew condemnation that year, prompting lawsuits.
The ACLU won the court order allowing them to reunite families separated at the border, including 1,030 children removed from their parents in a 2017 pilot program the government ran ahead of the implementation of its "zero tolerance" in 2018.
NPR reports that thousands of families were initially reunited within weeks.
Win McNamee/Getty Protesters and their children participate in a sit-in in the Hart Senate Office Building to mark the court-ordered deadline for the Trump Administration to reunify thousands of families separated at the border July 26, 2018 in Washington, DC.
Tuesday's filing says, however, that 545 children are still separated from their families and that, of the 485 children's families the steering committee has been able to contact, they have "yet to identify any families that definitively seek to have their child returned to their respective countries of origin."
The filing states the lawyers will advise the government "if and when any cases arisen in which a parent seeks to have their child returned."
The group searching for the parents has sent hundreds of letters to potential addresses in an attempt to reach parents of the 545 children and has set up a toll-free phone number for parents to call and be reunified with their children, the latest filing states.
Spencer Platt/Getty Hundreds of immigrant rights advocates and others protest against the Trump administration's policy that enables federal agents to take migrant children away from their parents at the border on June 1, 2018 in New York.
"It is critical to find out as much as possible about who was responsible for this horrific practice while not losing sight of the fact that hundreds of families have still not been found and remain separated," Lee Gelernt, a deputy director of the ACLU Immigrants' Rights Project, told NBC News. "There is so much more work to be done to find these families.”
Gelernt added: "People ask when we will find all of these families, and sadly, I can't give an answer. I just don't know.”
"We will not stop looking until we have found every one of the families, no matter how long it takes," he said.
Another group involved with the search efforts, Justice in Motion, has been among those looking for parents in Mexico and across countries in Central America, NBC News reports.
"While we have already located many deported parents, there are hundreds more who we are still trying to reach," the group told NBC News in a statement. "It's an arduous and time-consuming process on a good day. During the pandemic, our team of human rights defenders is taking special measures to protect their own security and safety, as well as that of the parents and their communities."
Chase Jennings, a spokesman for the Department of Homeland Security, described news reports on the border separations as a "narrative" and told PEOPLE in a statement that the department has taken "every step" to reunite kids separated from their families.
"The simple fact is this: after contact has been made with the parents to reunite them with their children, many parents have refused," Jennings said.
Still, Gelernt told NBC News, "The tragic reality is that hundreds of parents were deported to Central America without their children, who remain here with foster families or distant relatives."