In this Sept. 24, 2009 file photo, Mohammed Wali Zazi, left, leaves the federal courthouse in Denver with US Marshals. Zazi, who previously pleaded not guilty to conspiracy in the terror case against his son. – Photo by AP

NEW YORK: The father of a man convicted of plotting to bomb New York's subway system in an Al-Qaeda inspired scheme was found guilty Friday of obstructing a terrorism investigation.

A Brooklyn jury found Mohammed Wali Zazi, 55, guilty of destroying bomb making materials and conspiring to obstruct the investigation into his son's plot.

He “attempted to derail the federal investigation that was moving quickly to gather information,” the Department of Justice said in a statement Friday.

According to law enforcement authorities, the defendant's Afghan-born son, Najibullah Zazi, sent emails to a contact in Pakistan in a search for bomb making ingredients and then rented a car in Denver and drove toward New York City in September, 2009, in a plot to attack the New York City subway system.

The FBI conducted a covert search of his car and uncovered handwritten bomb-making notes, but after being tipped off by a local imam, the son then returned to Denver.

Mohammed Wali Zazi then lead a family effort to attempt to derail the federal investigation, said Justice Department.

“This defendant sought to conceal one of the most serious terror plots in recent times. He also enlisted others to help him spin his web of lies and to destroy key evidence,” said New York district attorney Loretta Lynch.

“Had the plot not been thwarted, it would have left Americans at grave risk,” she added.

Zazi will be sentenced on December 2 and faces up to 40 years in prison.

“Mohammed Wali Zazi may have been under no legal obligation to assist investigators. But he lied to them, impeding the investigation and obstructing justice. Being uncooperative is one's prerogative. Obstructing justice is a crime,” said FBI New York Assistant Director-in-Charge Janice Fedarcyk.