"I believe my crimes are very bad," Najibullah Zazi said on cross-examination. "If God gave me a second chance, I would appreciate it and will be a very good human being."
Earlier, Zazi told a federal jury at his alleged accomplice's trial that he slipped detonator ingredients into the city on Sept. 10, 2009, after the chemicals extracted from beauty supplies passed a test run.
Using code words, he then frantically emailed one of his al-Qaeda handlers to get the exact formula for building homemade bombs to go with detonators.
"The marriage is ready," Zazi wrote - signaling that he and two of his radicalized former high school classmates from Queens were ready to die as martyrs.
Zazi said the plot _ financed in part by $50,000 in credit card charges he never intended by to pay back - was abandoned after he noticed that everywhere he drove in New York, a car followed.
"I think law enforcement is on us," he recalled telling one of his co-conspirators, Zarein Ahmedzay. Later, he said he told the third man, Adis Medunjanin, in a text message, "We are done."
The 26-year-old Zazi testified for a second day at the trial of Medunjanin in federal court in Brooklyn. He was to return to the witness stand on Thursday for more cross-examination.
Prosecutors say that Zazi, Medunjanin and Ahmedzay - after growing upset over the U.S. invasion of Afghanistan and receiving terror training at an al-Qaeda compound in Pakistan - together hatched what authorities have described as one of the most serious terror plots since the Sept. 11, 2001, attacks.
Medunjanin, 27, a Bosnian-born naturalized U.S. citizen, has pleaded not guilty to conspiracy to use weapons of mass destruction, providing material support to a terrorist organization and other charges.
Medunjanin has denied he was ever part of an al-Qaeda operation. His lawyers have sought to show that - unlike Zazi and Ahmedzay - he had no direct involvement in the efforts to assemble bombs.
Zazi and Ahmedzay, both of Afghan descent, pleaded guilty in 2010 and were jailed without bail after agreeing to become government witnesses in a bid for leniency. Ahmedzay testified earlier this week.
Zazi recounted how, after leaving their Queens neighborhood for Pakistan in 2008, the three Muslim men met a top al-Qaeda operative they knew only as Hamad. Authorities say Hamad was Adnan Shukrijumah, a Saudi listed on an FBI website as a fugitive who plotted attacks for al-Qaeda worldwide.
Hamad told the three that they were best suited for an operation on U.S. soil. He also mulled over potential targets with them, including the New York Stock Exchange, Times Square and an unspecified Walmart store, Zazi said.
The men were drawn most to the subway because "it's the heart of everything in New York City," Zazi said Wednesday. The purpose, he added, was "to make America weak."
He added: "It was our choice."
At another al-Qaeda outpost in the South Waziristan region of Pakistan, Zazi said he learned how to distill explosives ingredients from nail polish remover, hydrogen peroxide and other products sold at beauty supply stores.
"It was very simple, and they're everywhere," he said of the chemicals.
Zazi took handwritten notes on bombmaking that were entered as trial evidence. They give instructions on "reducing oxidizing agent" and how to store acetone, warning it "is very sensitive - be careful."
In a later meeting in New York, the plotters decided to blow themselves up at three different locations inside the Manhattan subway system during the month of Ramadan, Zazi said.
On cross-examination, he acknowledged telling the FBI that they wanted to attack subway trains departing Grand Central Terminal at rush hour for maximum impact.
They hoped that "people would have a lot of fear," he said.
After leaving Pakistan, Zazi relocated to Denver, where he tried to blend back into society by driving an airport shuttle van. Behind the scenes, he bought beauty supplies, rented a hotel room with a kitchen and prepared acetone peroxide for a detonator, he said.
He also emailed an al-Qaeda operative asking for the recipe - "right away, please" - for a bomb made from flour and ghee oil. He estimated, that once in New York, it would take about five days to make what he called the "main charge."
By the time Zazi rented a car and drove to the city with the acetone peroxide in a glass jar, FBI agents were tailing him. When he realized that, he stopped at a Queens mosque and threw away chemicals, goggles and other bomb-building items, he said.
Ahmedzay flushed the acetone peroxide down a toilet as part of the cover-up, he added He also decided to go back to Colorado. But before he could leave, he discovered his rental car was missing. Authorities have said they secretly towed it away for a search before allowing him to retrieve it without letting on.
While trying to locate the rental, the would-be suicide bomber who had every reason to fear being caught testified that he still did what most people would do: "I called the police."
He flew back to Denver, where he was arrested about a week later.
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