A sign directs travelers to a security checkpoint staffed by Transportation Security Administration (TSA) workers at O'Hare Airport on June 2, 2015 in Chicago, Illinois. (Scott Olson/Getty Images)

Earlier today, Transportation Security Administration spokesperson Lisa Farbstein sent the following tweet from her verified account:

The photo, from the Richmond airport, shows a passenger's luggage containing $75,000 in cash. Farbstein asks, "Is this how you'd transport it?" Most people would not, but there is nothing illegal about simply checking a bag containing $75,000, or carrying it with you on the plane. Passengers aren't under any obligation to report large sums of cash unless they're traveling internationally, though the TSA recommends that passengers consider asking for a private screening.

Asked about the incident via e-mail, Farbstein said that "the carry-on bag of the passenger alarmed because of the large unknown bulk in his carry-on bag. When TSA officers opened the bag to determine what had caused the alarm, the money was sitting inside. Quite unusual. TSA alerted the airport police, who were investigating." Farbstein didn't respond to a question about whether posting photos of the man's luggage and property violated his privacy, nor did she offer any more details on the situation.

But the incident underscores the intense scrutiny some Americans face when they board public transportation carrying cash. A 2009 TSA blog post explained what the TSA does when agents encounter large sums of cash.

Sometimes a TSA officer may ask a passenger who is carrying a large sum of cash to account for the money. You have asked why such a question is posed and whether a passenger is required to answer.

In reacting to potential security problems or signs of criminal activity, TSA officers are trained to ask questions and assess passenger reactions, including whether a passenger appears to be cooperative and forthcoming in responding.

TSA officers routinely come across evidence of criminal activity at the airport checkpoint. Examples include evidence of illegal drug trafficking, money laundering, and violations of currency reporting requirements prior to international trips.

When presented with a passenger carrying a large sum of money through the screening checkpoint, the TSA officer will frequently engage in dialog with the passenger to determine whether a referral to law-enforcement authorities is warranted.

The TSA officer may consider all circumstances in making the assessment, including the behavior and credibility of the passenger. Thus, a failure to be forthcoming may inform a TSA officer’s decision to call law-enforcement authorities.

In this case, the cash was seized by a federal agency, most likely the Drug Enforcement Administration, according to Richmond airport spokesman Troy Bell. "I don't believe the person was issued a summons or a citation," he said. "The traveler was allowed to continue on his way."

If true, that would make this incident just the latest case of civil asset forfeiture at the nation's major transportation hubs. In recent months several high-profile stories have surfaced of passengers who had large sums of cash seized by the DEA, including a young man at an Amtrak stop, a college student at the Cincinnati airport, and a nail salon owner in New York. While the DEA took the cash in these cases under suspicion of its involvement in drug trafficking, no drug charges been filed in any of the cases.

This is all legal under the laws governing civil asset forfeiture, and there's no question that carrying large sums of cash is unusual. But many critics of the practice, including some in Congress, are calling for a major overhaul of civil forfeiture, saying too many people have had their assets seized inappropriately.