Derek Weekly joined Martindale Consultants as a Senior Regulatory Accountant following nearly 30 years with the State of Wyoming Department of Audit, where he spent the last 25 years serving as Audit Manager. In that role, he led, trained, and supervised teams conducting audits related to state severance taxes, state and federal royalties, and ad valorem valuations across oil, gas, coal, coalbed methane, and trona operations, with a specialized focus on oil and gas auditing in recent years.

Derek earned a Master of Business Administration (MBA) from Regis University and a Bachelor of Science in Business Administration from University of Wyoming.

Expertise and Focus Areas:

• Oil and gas severance tax audits
• State and federal royalty audits
• Ad valorem valuation reviews
• Regulatory compliance and valuation determinations
• Audit team leadership and training
• Sampling methodologies and audit strategy development
• Professional consultation for regulatory matters
• Supervising special projects within the Regulatory Division

During his time with the Wyoming Department of Audit, Derek was responsible for developing in-house auditor training programs and presenting mineral-related topics to agencies and legislative committees. He has also spoken at COPAS National Meetings, Colorado COPAS meetings, and PDI conferences.

Derek developed several sampling techniques that continue to be used today and were ultimately challenged and upheld at the Supreme Court level.

In his current role at Martindale, Derek provides training, valuation support, regulatory consultation, and leadership on specialized projects within the firm’s Regulatory Division.

In addition to his regulatory and audit background, Derek previously spent eight years as an adjunct faculty instructor at a Wyoming community college teaching business, marketing, management, and supervision courses. He also worked in product management for a direct marketing company, overseeing product development and marketing initiatives.