New York (CNN) -- A former New York cab driver from Afghanistan was found guilty by a federal jury Friday of obstructing a terrorist investigation and intentionally misleading police probing his son's admitted plot to bomb the city's subway system, prosecutors said.
Mohammed Wali Zazi, 55, the father of convicted terrorist Najibullah Zazi, faces a maximum of 40 years in prison and will be sentenced on December 2. He will by tried separately on a charge of visa fraud, prosecutors said.
"This defendant sought to conceal one of the most violent terror plots in recent times," Loretta Lynch, U.S. attorney for the Eastern District of New York, said in a news release. "He also enlisted others to help him spin his web of lies and to destroy key evidence. His actions, had they not been thwarted, would have left Americans at grave risk."
During the trial in a federal court in Brooklyn, prosecutors and defense attorneys offered drastically different accounts of Zazi's exchanges with investigators looking into charges against his son.
His attorney, Justine Harris, said in opening arguments that Zazi was totally unaware that his son was planning to blow up New York City subway stations with bombs planted in backpacks, which the son pleaded guilty to in February 2010.
"It's all a miscommunication, not a lie," Harris said. "He had no idea what was happening."
Harris argued that Zazi called his son, asking, "What is going on? What have you done?"
But prosecutor Andrew Goldsmith, in his opening statement, contended that the elder Zazi knew exactly what he was doing as he misled investigators.
The assistant U.S. attorney told jurors that Zazi tried to cover up his son's tracks by destroying valuable evidence, lying to FBI agents about people he knew and tipping off other suspects.
"(Zazi) is not charged with being a terrorist," Goldsmith said. "But he lied, and that is a crime."
A relative, identified as Amanullah Zazi, has admitted to helping Najibullah Zazi get terror training in northwest Pakistan's Waziristan region along the Afghan border. He pleaded guilty to related charges and cooperated with the government.
He testified in Mohammed Wali Zazi's trial that the elder Zazi told him FBI agents were looking for him and three other men and told him to destroy chemicals that might be part of any investigation.
Najibullah Zazi told authorities that while at the terrorist training camp, he "had discussions with al Qaeda about targets including the New York City subway system." Those attacks were planned for September 2009, prosecutors said.
Another relative caught up in the aftermath of the admitted bomb plotter's arrest was Najibullah Zazi's uncle, Naqib Jaji, who has pleaded guilty to conspiring to destroy evidence in the case against his nephew. Jaji agreed to cooperate with the government as part of his guilty plea, according to federal court papers.