NASCAR has suspended a crew member for Truck Series driver Chad McCumbee for failing a random drug test.

Andrew Crnkovic failed a random drug test conducted at Lowe's Motor Speedway on May 15. He has been suspended indefinitely.

He becomes the sixth crew member suspended this season under NASCAR's toughened drug policy. Jeremy Mayfield is the only driver to be suspended since NASCAR began random testing this year.

NASCAR does not reveal the substance found in an individuals' positive test.