A deaf Japanese tourist was illegally denied a sign-language interpreter while she was detained and interrogated after landing at the Honolulu International Airport, the American Civil Liberties Union of Hawaii said in a discrimination complaint.

The ACLU said Thursday it filed the complaint last month with the U.S. Department of Homeland Security's Office for Civil Rights and Civil Liberties. Her name is redacted from a copy of the complaint the ACLU provided. She fears retaliation by immigration officials, the ACLU said.

She arrived in Honolulu on the morning of January 31 to visit her boyfriend. Customs and Border Protection officials took her into an office to question her about her past as an international student in the United States, according to the complaint.

She requested an American Sign Language interpreter, but during hours of questioning she was forced to communicate by lip-reading and writing in English, the complaint said. In the late afternoon, she was handcuffed and taken to the Honolulu Federal Detention Center, where she was put into a cell overnight. "She was handcuffed behind her back, so there was no way for her to use her hands," the complaint said. "When detaining deaf individuals, it is appropriate to modify handcuffing practices to allow such individuals to use their hands to communicate with signs or in writing."

That's equivalent to silencing her, said Mateo Caballero, legal director for ACLU of Hawaii. "She was treated like a criminal," he said.

Customs and Border Protection received the complaint and will address the accusations after an investigation, agency spokesman Jaime Ruiz said in a statement, adding that accusations of mistreating travelers with a disability are taken seriously. Officers "receive extensive training in disability awareness and treat all travelers with disabilities with dignity, respect and professionalism," the statement said.

At the airport, customs officials took away her cell phone, so she wasn't able to alert her boyfriend, who waited 12 hours for her at a cafe near the airport, the complaint said.

At the detention center, which is near the airport, she again asked for an American Sign Language interpreter, but didn't receive one, the complaint said. Instead, staff members tried to ask her questions by using a Japanese translator on the phone, but the woman can't hear people talking on the phone, the complaint said.

"She felt humiliated," the complaint said.

The Bureau of Prisons, which oversees the detention center, didn't immediately respond to requests for comment.

The next day, she was taken to the airport for a flight back to Japan and her cell phone was returned. That's when she was finally able to let her family in Japan and her boyfriend know where she was, the complaint said.