Quazi Mohammad Rezwanul Ahsan Nafis, who claims to have al Qaeda connections, remains in custody since being caught in a federal sting on Wednesday.
His father, a bank vice president in Bangladesh, says he spent his savings to send his son to America to study. He insisted that Nafis was incapable of carrying out such an attack.
"My son can't do it," his father, Quazi Ahsanullah, said as he wept in his home in the Jatrabari neighborhood in north Dhaka, Bangladesh.
"He is very gentle and devoted to his studies," he said, pointing to Nafis' time at the private North South University in Dhaka.
But a spokesman for the university said Nafis was a terrible student who was put on probation and threatened with expulsion if he didn't bring his grades up. Nafis eventually just stopped going to school.
"He's not an evil person, but this is such an evil thing ... I'm just stumped," said Jim Dow, a former classmate, who also said Nafis gave him a copy of the Quran.
Nafis was arrested on Wednesday after he made several attempts to blow up a fake 1,000-pound the bomb inside a vehicle parked next to the Federal Reserve in lower Manhattan. The bomb was phony, but authorities said that Nafis' admiration of Osama bin Laden and aspirations for martyrdom were not.
While it is unclear when Nafis allegedly decided to turn to violence, he told an undercover agent in July that his purpose in coming to America was to wage "jihad."
The Associated Press contributed to this report.