Sources told Eyewitness News reporter Jim Hoffer that the suspect confessed when Port Authority detectives showed up at his house.
He surrendered to police with no problems. Police said he was being charged with defiant trespass, and that the charge was determined in coordination with Essex County prosecutors and federal officials. He will not face federal charges.
He was questioned at the airport by Port Authority police, who arrested him, and released shortly after midnight. Jiang is due to appear in Newark municipal court next week, according to Paul Loriquet of the Essex County Prosecutor's Office.
Speaking outside Haisong Jiang's home near the Rutgers University campus in Piscataway on Saturday, Ning Huang said he's known the 28-year-old for several years. Huang said Jiang is "a very good person" who didn't realize the ramifications of his actions on Sunday.
Andy Riu, who also described himself as a friend of Jiang, called him "very romantic." Both men said Jiang had been dating the woman for about a year and that he had flown to California several times to visit her.
The woman, a recent Rutgers graduate who lives in Los Angeles, was in New Jersey for a holiday visit.
"He loves his girlfriend," Huang said of Jiang, who has not commented publicly since he was arrested Friday night at his home. "He just went to say goodbye to her."
ABC News reports detectives had tracked down Jiang as they culled through a list of possible suspects.
Jiang lives in two-story home on a residential street of tidy, single-family homes near the Rutgers University campus in Piscataway. A neighbor, Claire Busby, said the home is rented by a group of Asian students.
Jiang is listed on the Rutgers Web site as a postdoctoral fellow in the school's biotechnology department.
"From every indication I've seen, everybody in there is good people," said Gene Wells, who lives next door to Jiang. "I've never had a problem with them."
Sen. Frank Lautenberg, who worked closely with the TSA, Port Authority and Continental Airlines after the incident last Sunday, applauded the arrest.
"With this arrest, law enforcement will be able to take a closer look into how and why this incident occurred and make sure that it never happens again," he said.
However, Lautenberg also expressed anger that Jiang faces a charge he described as a "slap on the wrist" and will only be given a fine of about $500.
"This was a terrible deed in its outcome - it wasn't some prank that didn't do any harm - it did a lot of harm because it sent out an alert that people can get away with something like this," said Lautenberg.
The breach led the TSA to shut down one of Newark Liberty International's three terminals for six hours, stranding thousands of passengers and contributing to major delays.
On a surveillance video released Thursday by the TSA and the Port Authority of New York and New Jersey, the guard is seen sitting at a security podium in an exit lane as passengers stream past on their way out of the terminal.
A man wearing a light-colored jacket stands inside a rope barrier, and the guard approaches the man, apparently telling him to move behind the rope.
Within a minute, the guard leaves the podium again and disappears into the crowd. A woman in a long white coat approaches the podium from inside the terminal; the man sees her and ducks under the security rope, and the two walk past, arm in arm.
The man was seen on a separate surveillance camera leaving the terminal about 20 minutes later, according to the TSA. He has not been found, and his identity remains a mystery.
A bystander waiting for an arriving passenger noticed the breach and told the guard. TSA officials then discovered that surveillance cameras at the security checkpoint had not recorded the breach and were forced to consult backup security cameras operated by Continental Airlines.
Jeff Pegues, Jim Hoffer, Adam Stephan, ABC News and The Associated Press contributed to this report.