A Department of Homeland Security agent told a Senate committee Thursday that she almost lost custody of her 1-year-old adopted daughter and was banned from owning a personal firearm after raising concerns over an obscure federal program that issues green cards to foreign investors.

Taylor Johnson, a senior special agent with the Immigration and Customs Enforcement (ICE) agency, testified along with several other whistleblowers who say they've also been retaliated against for speaking out against wrongdoings.

Johnson said her problems began after she started investigating the U.S. Citizenship and Immigration Services (USCIS) EB-5 program, which grants green cards to foreigners who invest $500,000 or more into U.S. businesses.

During her investigation, Johnson said she uncovered and reported mismanagement, public corruption and fraud, and questioned whether visa applicants were being scrutinized thoroughly enough, but was removed from the investigation and retaliated against.

"Some of the violations investigated surrounding the project included bank and wire fraud, and I discovered ties to organized crime and high-ranking politicians and they received promotions that appeared to facilitate the program," said Johnson. She found that "EB-5 applicants from China, Russia, Pakistan, Malaysia had been approved in as little as 16 days," and that the case files lacked "the basic necessary law enforcement queries."

"I found over 800 operational EB-5 regional centers throughout the U.S.," Johnson continued, saying this number was "disturbing" since the U.S. only allows 10,000 EB-5 applications a year.

"I could not identify how USCIS was holding each regional center accountable or how they were tracked once they were inside the U.S.," she said.

Johnson's managers received complaints from "high-ranking officials" at other agencies, and her investigation was shut down. She testified that she was then "subjected to a significant amount of harassment and retaliation."

She was first escorted from her work desk and barred access to her case files or other personal records. Her service firearm and credentials were also confiscated, as was her work vehicle.

Johnson said she was then "told I couldn't even carry or own a personal weapon, which is a constitutional rights violation."

"When an adoption social worker tried to contact and verify employment, she was told that I had been terminated for a criminal offense," Johnson told the committee. "I almost lost my 1-year-old child."

This testimony comes after a March report by DHS Inspector General John Roth concluding that former USCIS director Alejandro Mayorkas, now second in command at DHS, violated ethics rules by intervening in an "unprecedented" way to expedite EB-5 applications involving prominent democrats such as Senate Minority Leader Harry Reid and Virginia Governor Terry McAuliffe.