Sen. Dianne Feinstein, a California Democrat, testifies during a hearing before the Consumer Protection, Product Safety, Insurance, and Data Security Subcommittee of Senate Commerce, Science, and Transportation Committee in July on Capitol Hill.
CNN  — 

Sen. Dianne Feinstein of California called Thursday for the Senate Judiciary Committee to hold a hearing after two children died in the custody of Customs and Border Protection.

Feinstein, the top Democrat on the committee, made her request in a letter to GOP Sen. Lindsey Graham of South Carolina, who is set to chair the committee in the new year.

“These heartbreaking incidents are sadly consistent with previous reports of widespread abuse of children in immigration custody and the judgment of medical and mental health organizations that Border Patrol facilities are not adequately staffed or equipped to properly care for children,” Feinstein’s letter read.

Earlier this month, the Department of Homeland Security said a 7-year-old Guatemalan girl, Jakelin Caal Maquin, had died hours after being taken into Border Patrol protection. The agency said this week that an 8-year-old Guatemalan boy, Felipe Gomez Alonzo, had died late Christmas Eve in the custody of Customs and Border Protection.

Homeland Security Secretary Kirstjen Nielsen said Wednesday that all children in Border Patrol custody had received medical screenings and she had “directed a series of additional actions to care for those who enter our custody.” Customs and Border Protection Commissioner Kevin K. McAleenan said Wednesday that he was reiterating his calls for more help and resources from Congress.

In her letter, Feinstein cited the deaths of the two children along with reports of a hospitalized 5-month-old and murdered children in Tijuana.

She said she had reached out to McAleenan “but have not received answers to explain why these deaths occurred.”

Nielsen reiterated Wednesday that six migrants, none of whom were children, died in the custody of Customs and Border Protection during fiscal year 2018. She noted it had been more than 10 years since a child has died in the agency’s custody.

Feinstein’s letter followed an announcement Wednesday from House Minority Leader Nancy Pelosi, a California Democrat, that Congress would investigate the children’s deaths. McAleenan said his agency reported all deaths in custody to both its office of professional responsibility and the DHS inspector general.

Later on Thursday, a group of key House Democrats issued a statement calling for DHS to preserve evidence related to the deaths of the two children and saying their hearings would take place once they assume control of the House next month.

“This evidence includes, but is not limited to, medical records, logs of health and welfare checks, and surveillance videos at all relevant Customs and Border Protection holding facilities, forward operating bases, and processing centers,” the statement read.

CORRECTION: This story has been updated to spell Felipe Gomez Alonzo’s name correctly.

CNN’s Geneva Sands, Kate Sullivan and Sonia Moghe contributed to this report.