(NEW YORK) -- A Boston-bound man arrested at Los Angeles International Airport wearing what appeared to be a bulletproof vest and transporting weapons in his luggage puzzled investigators by saying, "Hey, this is a game."
Yongda Huang Harris, 28, a naturalized U.S. citizen who teaches English in China, was otherwise uncooperative with detectives and the FBI, which had an agent sit in on the questioning at the airport.
Like many of the known facts about Harris -- now facing a federal charge for transporting hazardous material on an airplane -- the meaning of the statement, "This is a game," remained unclear to investigators.
One of them told ABC News, "It could mean he thought the questioning was a game. He could mean the whole thing -- the vest, the stuff in his checked baggage, was a game."
At least once during his flights from China to Korea to Japan and on to Los Angeles, officials believed, Harris set off alarms and underwent secondary screening, authorities told ABC News. Following that screening, it appeared that Harris continued wearing his vest all the way to the United States, where he was stopped and detained upon entry.
Harris told U.S. investigators that he was puzzled that they would hassle him over his wearing of the bulletproof-style vest and asked them why they were doing so after he had been stopped in Korea and in Japan and allowed to proceed.
The bulletproof-style vest, in fact, "would not have stopped a bullet," according to U.S. authorities. It was a Chinese-made knockoff of a vest and not, in fact, an actual ballistic vest, investigators said.
"There is no reason to believe he did not have it on when he began the trip in China," one senior investigator said. "We believe he boarded with it. The question is how did it happen."
Harris was pulled aside in customs Friday at the Los Angeles airport for a secondary baggage inspection, when an officer noticed Harris was wearing the vest.
The officer asked Harris if he had anything he would like to declare in his checked luggage. Harris told the officer he had a knife, but when his bag was searched, the officer found an array of suspicious items.
In addition to the smoke grenade, officers found three leather-coated black-jack billy clubs, a collapsible baton, a full-face respirator, several knives and a hatchet. Officers also found body bags, a tyvex biohazard suit, various masks, duct tape, hand cuffs, leg irons, flex cuffs, oven mitts and cooking tongs.
It was not clear why Harris had the items.
On Harris' laptop, investigators found Japanese fantasy rape writings, pornography and a copy of the "Poor Man's James Bond," a popular text among dissidents and anarchists that has exhaustive information on the use of terror tactics.
Harris earlier in 2012 was in Japan on a trip that lasted approximately 10 or 11 days.
According to authorities, Harris began his latest trip in China, where he purchased a one-way ticket to Korea.
In Korea, he purchased the ticket that took him through Japan to LAX. His final destination was to be Boston, authorities said.
Though he was arrested Friday, because of the federal holiday Harris made his initial appearance Tuesday in a Los Angeles federal court and remained in federal custody. Harris was scheduled to be back in court Friday for a detention hearing.
The Department of Homeland Security and the Transportation Security Administration also are looking into the matter and how it could have been avoided.
"TSA will review, in concert with aviation security officials in Korea, how a prohibited item was able to travel in checked baggage and implement any necessary changes," DHS Director of Communications Matt Chandler said.
Harris came to the United States as a child, was raised in the Boston area and attended Boston University. He had an interest in science, investigators said, and calculations or formulas were found in a diary in his possession.
Harris was being represented by criminal defense attorney Steven A. Seiden, who is also representing the controversial anti-Islam filmmaker Nakoula Basseley Nakoula.
Reached for comment, Seiden's office described Harris as a highly intelligent and diligent student who attended excellent schools in Boston and has no criminal history or violent tendencies.
Copyright 2012 ABC News Radio