WASHINGTON >> The bipartisan leaders of the Senate Judiciary Committee asked federal investigators late today to examine allegations of sexual, physical and emotional abuse of immigrants held at government detention facilities, saying the mistreatment may have been occurring since 2014 or earlier.

With President Donald Trump already under fire for separating thousands of migrant children from their detained parents, the request for an investigation by Sens. Chuck Grassley, R-Iowa, and Dianne Feinstein, D-Calif., elevated yet another issue to the administration’s list of immigration problems.

“These allegations of abuse are extremely disturbing and must be addressed,” Grassley and Feinstein wrote. “This is not a partisan issue as reporting suggests many have been occurring for years. Immigrant families and children kept in federal custody deserve to be treated with basic human dignity and respect and should never be subjected to these forms of abuse.”

The letter, based on articles by The Associated Press and other news organizations, says the allegations suggest “a long-term pattern” of mistreatment. Those reports describe claims of abuse over the last few years.

The Judiciary committee has scheduled a hearing for Tuesday on the Trump administration’s separation of thousands of migrant children from parents detained entering the U.S. without authorization. Trump abandoned that policy after he came under intense bipartisan criticism, but hundreds of children remain apart from their families, including more than 400 whose parents have been deported without them.

The senators want the inspectors general for the departments of Homeland Security and Health and Human Services to investigate the abuse allegations immediately and to release any previous investigations into the charges. They also want the investigators to study “the adequacy of policies and procedures” used by U.S. Immigration and Customs Enforcement, a branch of Homeland Security, and by Health and Human Services to prevent abuse.

The AP reported last month that children held at an immigration detention facility in Virginia said they were beaten while handcuffed, locked in solitary confinement and left nude and cold in concrete cells.

A civil rights lawsuit has been filed alleging mistreatment at the Shenandoah Valley Juvenile Center in Roanoke, Virginia, from 2015 to 2018. The alleged victims, Hispanic youths held there for months or years, have submitted sworn statements in the case.

Lawyers for the facility have denied the alleged abuse. Many of the children have been accused by immigration officials of belonging to MS-13 and other violent gangs, an activity Trump has used to justify his “zero tolerance” policy of prosecuting immigrants caught entering the country without permission.

The senators’ letter also cited a New York Times report this month about two female migrants who described sexual abuse at detention facilities in Texas and Pennsylvania. Immigration and Customs Enforcement has reported 1,310 cases of sexual abuse against detainees from 2013 to 2017, the report said.

A June report in The Dallas News described alleged sexual abuse at a detention center near Austin, Texas, in 2017, and The Arizona Republic reported alleged inappropriate contact involving a teenage boy in 2015 and a girl who accused a staffer of making suggestive comments in 2017 at facilities in Glendale and Tucson, Arizona. The lawmakers’ letter cited those reports as well.

Last week, U.S. District Judge Dana Sabraw commended the Trump administration for reuniting parents in its custody with their children while faulting it for leaving hundreds of families still apart and warning that a better system must be in place. Trump seized on the praise, tweeting today that “a highly respected Federal judge” had said that the “‘Trump Administration gets great credit’ for reuniting illegal families. Thank you, and please look at the previous administrations record – not good!”

Officials at Homeland Security and Health and Human Services did not immediately respond to requests for comment emailed to their press offices.