'Wheel of Fortune' Jim Thornton Featured on Tuesday's Show Amid Sony Investigation

9:45 PM PT -- Jim Thornton's attorney tells TMZ ... the announcer "did not engage in any illegal conduct, was not arrested, and has not been charged with any crime. When questioned about the complaint made by a fellow passenger on the flight, law enforcement spoke to him for five minutes or less, immediately determined that no wrongdoing had occurred and told my client he was free to go."

Jim Thornton appeared on Tuesday night's pre-taped episode of "Wheel of Fortune" ... hours after Sony Pictures Television announced an investigation into the longtime announcer.

Ryan Seacrest tossed to Jim, asking him what was on the wheel that night ... and Jim gave his usual spiel about the guests and prizes. Worth noting -- "Wheel of Fortune" usually tapes episodes a couple months in advance.

As TMZ first reported, Jim was detained by law enforcement after a flight in May. Cops were called after a passenger on the plane complained about him.

Sony Pictures Television previously told TMZ on Tuesday ... "We have recently been made aware of allegations concerning Jim Thornton."