Industrial Leak Testing employs Level I, II and III inspectors trained and certified as recommended in section five of  the Boiler and Pressure Vessel Code from The American Society of Mechanical Engineers as well as NAS-410 and many other test standards and specifications. 

While some companies claim to be in accordance with ASNT-TC-1A from  The American Society for Nondestructive Testing and simply appoint a company Level III inspector, Industrial Leak Testing's Level III inspector has passed both the basic and method examinations and is certified directly through ASNT. 
(Certification # 118799 Leak Testing)

We suggest visiting the ASNT web site at the address below to verify the certification of your current NDT professional. 
http://www.asnt.org/publications/rediref/certlist/intro.htm