The TSA has launched an investigation of a passenger in San Diego who left the airport after opting out of an invasive body scan and criticizing the proposed alternative pat-down.

John Tyner, a 31-year-old software programmer, recorded the encounter on his mobile phone and posted it to his blog. From there, it quickly went viral, tapping a groundswell of frustration over TSA's procedures.

But far from backing down, the TSA told local reporters that it's now investigating the passenger, who may face an $11,000 fine if the agency sues him.

"What he's done, he's violated federal law and federal regulations which states once you enter and start the process you have to complete it," TSA's San Diego security director told the Fox 5 News.

Tyner was at the San Diego airport last Saturday with his father-in-law and brother-in-law on their way to South Dakota for a three-day pheasant-hunting trip. Tyner said he checked the TSA website beforehand and didn't see San Diego International Airport on a list of facilities using new invasive scanners that take a strip-search image of passengers beneath their clothes. But once in the security line, he saw that the airport was indeed using the scanners. He was in line to go through a metal detector when an agent directed him through the new body scanner instead.

"There was a certain percentage of people who were willingly going through the scanner," Tyner told Threat Level. "Then, every time the scanner was empty, they would just grab the next person in the line for the metal detector and send them through the scanner."

Due to privacy and health concerns, Tyner opted out of the scan in favor of a pat-down. But when the TSA agent explained in detail the agency's new policy for "enhanced" pat-downs – which includes using the front of hands and fingers to touch passengers in their groin – Tyner balked.

"If you touch my junk," he told the agent, "I'll have you arrested."

The agent called his supervisor, who told Tyner that if he wasn't comfortable with the enhanced pat-down "we can escort you back out and you don't have to fly today."

Tyner told the agent, "I don't understand how a sexual assault can be made a condition of my flying."

When the agent replied that a pat-down was not considered a sexual assault, Tyner said, "It would be if you were not the government."

The TSA supervisor told him, "By buying your ticket you gave up a lot of rights."

Tyner's brother-in-law had already been directed through the scanner and complied. His father-in-law was on the other side of security. Tyner isn't sure if he went through the metal detector or the scanner. But while Tyner was being interrogated, he saw numerous passengers pass through the metal detector and go on to their flights without undergoing a pat-down.

Tyner told the agents he was happy to go through the metal detector and even submit to a regular pat-down, but not one that involved a groin check. His father-in-law, a former deputy sheriff, told the agents to be reasonable.

"Just let him go through the metal detector and this will all be over," his father-in-law said. But the agents insisted that regardless of the fact that Tyner had initially been set to go through the metal detector before agents directed him to the scanner, once he rejected the scanner, he had to undergo the enhanced pat-down. He could either submit, or leave the airport and not fly. Tyner chose the latter option and was escorted to the American Airlines ticket counter to get a refund.

He was on his way out of the airport when a man in a sport coat approached and told him he could not leave the airport until he'd completed the security screening, even if he had no intention of getting on an airplane. The man, whom Tyner believes was with the TSA, told him that he'd be subject to prosecution and a civil fine if he left without being screened. Tyner told the man to sue him and walked out of the airport.

Tyner said although his father-in-law continued the trip without him, he later told Tyner he was proud of him for standing up for what he believed was right. Tyner has received calls from lawyers with the American Civil Liberties Union and the Rutherford Institute to discuss the issue and says he has also received offers of support from the public to help pay any fine or legal defense costs he may face.

On Monday, the TSA defended its actions.

"We want to be sure that everyone on a plane can be assured that the people with them received the same screening process," Michael Aguilar, the TSA's security director in San Diego, told reporters, despite the fact that screening actually varies greatly among passengers, some of whom are allowed to pass through metal detectors without a pat-down or scan.

Aguilar added that Tyner's recording of the incident created suspicion that he might have staged the incident. Aguilar insisted that the TSA had no plans to change its procedures.

But a growing movement among pilot associations and traveler-rights groups suggests the TSA is under increasing pressure to reconsider that stance.

Several groups have called for a National Opt-Out day on Nov. 24, traditionally the busiest travel day of the year, to protest the TSA's attempt to force passengers to undergo invasive scans or face an intrusive pat-down.

The U.S. Senate Committee on Commerce, Science, and Transportation is also holding a hearing on Wednesday to discuss TSA oversight.

Privacy groups such as the Electronic Privacy Information Center are seeking a court order to halt the use of invasive scanners, saying the scanners are illegal and violate passenger privacy.

They also say the government has done little to ensure that images taken by the devices are not saved. The TSA has asserted that security scanners cannot store pictures, but security personnel at a courthouse in Florida were found to not only have saved about 35,000 images but shared some of them among colleagues in order to humiliate one of their co-workers. On Tuesday, Gizmodo released 100 of the images, which the government released after EPIC sued it in a Freedom of Information Act request.

Scientists have expressed concern that radiation from the devices could have long-term health effects on travelers. EPIC filed a separate FOIA request last summer to obtain reports and other information the TSA used to determine the health effects of the devices before deploying them in airports. The civil liberties group announced on Tuesday that it was suing the agency to comply with the request.

Consumer rights advocate Ralph Nader told reporters on a call on Tuesday that the technology was ineffective – since it fails to detect all explosives – and has not been subjected to proper analysis to determine the health risks.

"As more people experience the invasive scanners and pat-downs, including congressional members and celebrities, the more attention the issue will get," he said.

Kate Hanni, founding director of FlyersRights.org, said that her organization's hotline has "been blown up with calls complaining about the scans and pat-downs." Members with the 30,000-strong organization expressed concerns about health risks and about whether the TSA conducts background checks on agents to screen pedophiles out of the agency.

James Babb, co-organizer of WeWon'tFly.com, one of the grassroots campaigns behind the National Opt-Out day, told reporters on the call, "I believe the TSA has suckered Americans into a false sense of security with these scanners of dubious value."