The United Nations high commissioner for human rights, Volker Türk, on Friday raised the alarm internationally about deaths in US government immigration custody and called for “prompt, independent, impartial and effective investigations”.

Türk’s call came as the Trump administration faced investigations by watchdogs at its own Department of Homeland Security (DHS) into deaths and use of force against people detained in its expanding immigration detention system across the country.

Donald Trump is coming under increased pressure amid the surge in deaths within Immigration and Customs Enforcement (ICE) custody, which comes under the DHS, including a significant series of suicides – and a lack of transparency from the US president and his federal agencies.

“Those responsible for violations of the law must be held to account, and the rights of the victims’ families to truth, justice and reparation, and guarantees of non-recurrence must be upheld,” Türk said, in a statement.

Türk’s call on Friday followed an announcement by the federal government’s Homeland Security watchdog office that it will be investigating deaths in ICE custody and use of force on detainees in immigration jails. Similarly, it follows a scathing report by Human Rights Watch released this week about deaths in ICE detention. The report alleged “violations of ICE policy and international human rights law”.

Türk also expressed alarm over the use of solitary confinement inside ICE detention centers.

“All these factors exacerbate vulnerability and raise serious concerns as to whether some of these deaths in ICE custody could have been prevented,” Türk added. The UN has previously said that the use of solitary confinement for more than 15 days is considered “torture”, in a report that accused the US of using the punishment excessively in its prisons and jails, as well as overuse worldwide.

The US inspector general’s office within the DHS, meanwhile, announced the two separate investigations on Wednesday, after an increasing number of deaths in ICE custody and multiplying allegations of abuse and mismanagement inside ICE facilities.

“We are conducting this evaluation because of an increase of detainee deaths in ICE custody each year since fiscal year 2022,” the DHS inspector general’s office said when announcing its internal investigation. The watchdogs will look at whether “systemic factors, policies, or processes” played a role in deaths between 1 October 2021 and 31 March of this year.

Since the Trump administration took office again in early 2025, ICE has dramatically increased its number of arrests and detentions of immigrants nationwide, attempting to fulfil Trump’s campaign promise of “mass deportations”. Early in the administration, top Trump officials set a goal of 3,000 arrests per day, leading to a surge in ICE operations nationwide and protests in opposition to the harsh deportation campaign.

Mortality in ICE custody is at its highest level in over a decade, according to Human Rights Watch. The US-based advocacy’s report released this week calculates that in the first 500 days of Trump’s second administration, 52 people have died in ICE custody in the US.

A separate report by the University of California, Los Angeles (UCLA) Law Behind Bars data project found such deaths have reached the highest levels since 2004, when 32 people died in the DHS’s custody, a figure matching other reports about last year.

The administration has opened new detention centers and is considering further expansion of its detention network, boosting its capacity to detain up to 90,000 people nationwide, according to the UN. There are now about 60,000 people detained by ICE. The majority of ICE’s detention centers are run by private prison companies.

Türk added on Friday that immigration detention should be an “exceptional measure of last resort” and should generally be avoided for people with significant medical or mental health conditions, as well as pregnant women. He said that children should not be in immigration detention at all. The second Trump administration restarted family detention and has locked up thousands of children, including very young kids and babies, as well as pregnant women.

The DHS has repeatedly denied there has been a surge of in-custody deaths, despite its own data and press releases indicating the contrary.

The DHS did not respond specifically to the remarks and allegations by Türk and the HRW report or the announcement of the watchdog investigations.

When a detainee dies in ICE custody, the agency is required to inform the public within 48 hours and later release further reports. Human Rights Watch said there was a shocking lack of transparency about deaths inside ICE’s secretive network of facilities.

“ICE so severely limits the information it provides to Congress, families and the public that oversight is nearly impossible,” said Dr Katherine Peeler, a co-author of the report and assistant professor of pediatrics at Harvard Medical School. “In the cases where we do have access to ICE and outside hospital records, we are seeing a breathtaking breach of the duty of care.”

The DHS inspector general typically investigates whether agencies within the department, including ICE, are following policies and makes recommendations.

The DHS inspector general’s office is the last watchdog left within the department. The gutting of other DHS oversight offices means thousands of cases related to conditions in immigration detention, deaths in custody and officers’ use of force are not being investigated, the Guardian has reported.

Türk on Friday urged “the full restoration and strengthening of independent oversight mechanisms for immigration detention.”.