Heidi Dalibor admitted to ignoring four notices from the library in addition to two phone calls, two letters and a citation that included a court date, WISN-TV, Milwaukee, reported Friday.
"I said, what could they possibly do? They can't arrest me for this... I was wrong," Dalibor said.
Dalibor was released after paying her $170 fine.
"I completely take responsibility for not paying my fine on time and not going to my court date," Dalibor said.
However, the woman said the library will now never get the copies of "White Oleander" and "Angels and Demons" back on their shelves.
"I still have the books and I don't plan to return them because they're paid for now," Dalibor said.
Grafton Police Chief Charles Wenten said officers were merely following the law when they arrested the woman for her outstanding library fines.
"None of this would have been necessary if she followed the agreement and returned the books," he said.