Quazi Mohammad Rezwanul Ahsan Nafis, 21, who was arrested Wednesday by New York federal authorities after a prolonged sting operation, came to the United States in January to study cyber security at a college in Missouri.
Speaking to CNN in Dhaka, Bangladesh, his banker father Quazi Mohammad Ahsanullah described his son as a timid person and rejected any terror accusations against his son.
"I don't believe my son has any link to any terror groups," the father said. "I urge the government of Bangladesh to bring back my son." He told CNN he learned about his son's arrest in New York from a relative.
"We're really stunned," the father said. "We couldn't believe our eyes. ... We couldn't believe our ears. It came to us out of the blue."
The BBC quoted the father that the allegations against his son are "totally false" and that his son is "totally innocent."
Nafis has been charged with attempting to use a weapon of mass destruction and plotting to provide material support to al-Qaida.
"He went to the United States only to study. Not to do any kind of activity. He is my only son," the father told the BBC.
"I am 100 percent sure that he had no contact with anybody. He has been victimized."
Bangladesh's Daily Star newspaper quoted the father, a senior bank vice-president, as saying he last talked to Nafis on the cell phone Wednesday morning. Nafis has an older sister, reported to be a college lecturer.
In Washington, State Department spokeswoman Victoria Nuland confirmed Nafis had a valid student visa, reportedly to study cyber security at a college in Missouri.
"Let me start by confirming that the suspect did have a student visa to attend a legitimate academic program in the United States, for which he was qualified," adding "every single one of these visas is adjudicated overseas."
"Visa decisions are made in accordance with applicable law and Department regulations. Each case is looked at on a case-by-case basis, taking into account all of the information contained in the U.S. Government databases, and in consultation with other government agencies," she said.
Nuland declined to answer other question relating to adjudication of the suspect's visa.
The criminal complaint against Nafis, who has been charged with conspiring to use weapons of mass destruction and providing material support to al-Qaida, said after arriving in the United States in January on a student visa, he tried to recruit people to form a terrorist cell to help him carry out his attack.
Nafis, who faces life in prison if convicted, also allegedly wanted to kill President Obama, The New York Times, quoting a senior law enforcement official, reported earlier. The report said Nafis, as described in court papers, had been eager to win al-Qaida's respect.
The U.S. Federal Bureau of Investigation said Nafis was arrested Wednesday in downtown Manhattan after he allegedly tried to set off a fake 1,000-pound bomb in a sting operation conducted by the New York FBI Field Office's Joint Terrorism Task Force and New York police.
New York police Commissioner Raymond Kelly said prior to Wednesday, authorities had discovered 15 plots since the Sept. 11, 2001, terrorist attacks on New York and Washington. He warned al-Qaida operatives and those they have inspired have "tried time and again to make New York City their killing field."
Assistant FBI Director Mary Galligan said attempting to destroy a landmark building and kill or maim untold numbers of innocent bystanders "is about as serious as the imagination can conjure."
The FBI undercover agent reportedly had been working with Nafis since July and had been recording the suspect's statements. The suspect is reported to have said: "I don't want something that's like, small. I just want something big. Very, very, very, very big, that will shake the whole country."
Britain's Daily Telegraph said Nafis also reportedly told FBI agents he was inspired by the videos of Anwar al-Awlaki, an extremist who sent out hate sermons online. Awlaki, raised in the United States, was killed last year in a drone strike in Yemen.
CNN reported Bangladesh police had begun investigating whether Nafis had any terror link, police said.
"We're not officially informed by the United States about the alleged plot and the subsequent detention, but we're looking into if Nafis had any terror link before leaving Dhaka," chief of Dhaka police detectives Monirul Islam told CNN.
He said Nafis' kind and relatives were questioned about his past activities.
"We haven't arrested anyone ... We've just started the investigation, and we're yet to find any terror link of Nafis ... but we'll continue the investigation and interrogate more people who know Nafis. It may be his friends, teachers, neighbors and others," he said.
The USA Today quoted U.S. authorities that Nafis' arrest showed that terrorists are determined to strike the United States.
The report said despite significant security upgrades, terror analysts said New York's status as the world's financial center and its iconic images make it attractive to terrorists.
"New York is like the Super Bowl for terrorists, and it may always be," said Don Borelli, former assistant agent-in-charge of the FBI's New York Division. "There is a familiarity with New York. Even in the most remote places in the world, people know what New York means to America."