An airline stewardess on an American Airlines flight from Argentina to Miami on Tuesday saw a man leaving his seat, wandering around the plane, and sitting in empty seats next to other passengers. 

Friendly guy? Definitely very odd behavior. 

The man, Diego Sebastian Radio, 29, was arrested after leaving the plane.

He was accused, and admitted to, stealing more than $10,000 from other passengers, in a shifty scheme that involved ripping them off without their knowledge. 

He is being held on a $250,000 bond at the Federal Detention Center in Miami.

He had stolen cash and credit cards from at least two unsuspecting passengers. The thefts were discovered when the flight attendant told passengers to check their belongings. One woman discovered she was missing a sizable amount of money. Another discovered that her wallet was open and she was missing two credit cards and some cash. 

When officers patted down the thief in Miami, they found the stolen items on him, including the stolen credit cards.

Not a coincidence. Not a friendly guy.