Immigrant advocacy groups have filed nearly a dozen complaints and lawsuits against U.S. Customs and Border Protection across the country, claiming federal agents and officers mistreated and discriminated against illegal immigrants and U.S. citizens alike.

The groups alleged Wednesday that officers at Dulles International Airport outside Washington, D.C., were complicit in sending a 4-year-old American girl to Guatemala without giving her parents a chance to retrieve her. Officers also detained a naturalized citizen who had been working with farmworkers in New York, kept women in cold detention cells in Texas and lied on an arrest report that led to an illegal immigrant’s detention in Washington state, the advocacy groups said.

The complaints are the latest in a series of legal actions taken against U.S. Customs and Border Protection and U.S. Border Patrol from immigrant advocacy groups, who have long sought to reform the agency’s conduct on the southern and northern border. The cases involve federal administrative complaints against the agency and lawsuits filed in federal court.

Some seek monetary damages.

“By filing these cases, we’re aiming to send a message to CBP that it’s not above the law,” said Trina Realmuto of the Boston-based National Immigration Project.

A U.S. Customs and Border Protection statement said the agency can’t comment on pending litigation, but adds that it stresses honor and integrity from its officers and agents.

“We do not tolerate misconduct or abuse within our ranks and we fully cooperate with all investigations of alleged unlawful conduct, on or off duty, by any of our CBP employees and contractors,” the statement said.