Within hours of being booked at a Border Patrol station in far West Texas, two teenage sisters from Guatemala alleged that an agent conducted an improper strip search.

The agent denied the allegations, including the sisters’ claims that he touched their genitals. He insisted that he had only fingerprinted them before taking them back to their cell.

Investigating the case came down to the sisters’ word vs. the agent’s. As in dozens of similar cases, government investigators sided with the agent.

Advocates say the case — outlined in a report compiled by internal investigators — shows the kinds of hurdles detained immigrants face when they make claims of misconduct.

“These women were actually, for lack of a better word, lucky that their case was investigated,” said Christina Mansfield, co-founder of the advocacy group Freedom for Immigrants. “They are in the extreme minority in that regard.”

The sisters, ages 17 and 19, entered the United States without legal permission in July 2016. They were detained by Border Patrol agents shortly after crossing the border.

The Associated Press received a redacted copy of the investigative report through the Freedom of Information Act. It shows that investigators determined that the sisters’ allegations could not be substantiated because of a lack of physical evidence.

Immigration advocates say the Department of Homeland Security’s Office of Inspector General, which reviewed the sisters’ case, rarely recommends action against officers. A study by Freedom for Immigrants found that between January 2010 and July 2016, the inspector general received 84 complaints of coerced sexual contact against U.S. Customs and Border Protection, which includes Border Patrol. The inspector general opened just seven investigations, none of which is known to have led to charges, according to the study, which was conducted by examining government records.

The study found a similarly low number of cases were investigated by the inspector general for detention facilities operated by U.S. Immigration and Customs Enforcement.

CBP would not directly address the sisters’ case or whether it disciplined the agent involved. The agency said it is committed to treating detainees with “professionalism and courtesy.”

— Associated Press