A worker led the "American Idol" judge and a companion around the mandatory screening process before they boarded a Southwest Airlines flight headed to Burbank, Calif., Thursday afternoon, said Elaine Sanchez, a spokeswoman for McCarran International Airport.
She said she could not confirm reports that the employee was trying to help the pop star avoid a swarm of fans.
Federal Transportation Safety Administration officials were alerted to the security breach while the plane was in the air, TSA spokeswoman Jessica Altschul said.
"We're conducting an internal investigation to see who exactly was responsible," she said.
The person who took Abdul past the checkpoint worked for an airport tenant, but not Southwest, Sanchez said. She said she could not identify the worker while the investigation was under way.
An Abdul spokeswoman did not return a phone call.