He was briefly interviewed by federal agents and sent on his way - gone, but not forgotten. The very same day, New York Police Department detectives began surfing the Internet for information about him.
Authorities say the police department's Intelligence Division investigators found a treasure trove of evidence against Shehadeh that help make the homegrown terror case against him. The evidence, they say, also offered more proof that the Internet has become an incubator for extremism, and demonstrated how a special NYPD unit identifies and tracks cyberthreats.
Shehadeh, 21, failed to get into Pakistan. The New Yorker was arrested last week in Hawaii on charges he made false statements.
He was in federal custody and was expected to eventually appear in federal court in New York. No date was set.
There was no immediate response to a message left Tuesday with Shehadeh's attorney in Honolulu. A spokesman for the U.S. attorney's office in Brooklyn declined to comment on Tuesday.
The NYPD investigative unit was formed after the Sept. 11, 2001, terrorist attacks - part of the department's strategy for homeland security that has resulted in the redeployment of about 1,000 officers to counterterrorism duty. Many of the unit's members are foreign-born and fluent in languages like Arabic and Farsi.
The NYPD assisted in another case earlier this year in which two men were arrested at Kennedy on charges they wanted to travel to Somalia to get terror training. Investigators allege they were radicalized in part by other Americans preaching violent jihad over the Internet.
In Shehadeh's case, the NYPD investigators discovered that he had created a radical roadmap with websites that posted speeches by al-Qaida leaders including Abu Yahya Al-Libi and Ayman al-Zawahiri, authorities said.
A criminal complaint says he also put up a photo of himself wearing a keffiyeh headdress, another snapshot of a man holding a sign reading "Jihad is Our Way," videos of Osama bin Laden and a recording titled "Benefits of Jihad in Our Times." One of his sites had "a montage of still images of jihadist fighters under the heading, 'What is the least we can do?"' the complaint said.
In one militant missive, investigators say he wrote: "My brothers of the revolution of Islam, I am with you as long as you keep struggling. Trust me, there are many brothers and sisters in America that are ready to speak up. They just need a push."
The investigators followed Shehadeh's Internet footprints to business records showing his site emanated from two Staten Island addresses. In June 2008, members of the joint FBI-NYPD terror task force went to one of addresses to interview him. The complaint said Shehadeh told them he had tried to travel to Pakistan to "study Islamic law."
Four months later, Shehadeh showed up at a Times Square military recruiting station and tried to sign up, authorities said. An unidentified friend he had worshipped with later told investigators Shehadeh had hoped the Army would deploy him to Iraq, where he could desert and join insurgent forces.
Investigators closed in on Shehadeh after he again tried to travel to the Middle East, this time to Jordan. As with Pakistan, he wasn't allowed into the country and came home, where he was greeted by FBI agents asking about his websites.
Shehadeh at first denied he had started the sites, the complaint said. He later admitted one was "designed to mirror and reformat the teachings" of radical U.S.-born Muslim cleric Anwar al-Awlaki.
Al-Awlaki is believed to help inspire recent attacks including the Fort Hood shooting, the Times Square bombing attempt and the failed Christmas Day airline bombing.
In February, Shehadeh met with FBI agents to try to talk them into taking him off a "no-fly" list, the complaint said. He also insisted that he had no interest in jihad, it said.
But in April, Shehadeh told agents he once believed "he needed to get back at the United States and that if he died as a martyr in Pakistan he would have received 72 virgins as a reward," the complaint said.