Casselle represents publicly traded and closely held companies in sensitive, high-stakes internal and regulatory investigations and enforcement matters across a broad spectrum of commercial enterprises and industries – including financial services, energy, and health sciences. These matters often involve allegations of corporate malfeasance, professional misconduct, market manipulation, compliance and operational failures, and violation of the federal securities laws.

Casselle takes on matters at every organizational level, ranging from discrete matters involving sensitive allegations made by and about frontline employees to “bet-the-company” matters involving credible allegations of misconduct by officers, directors, and entire divisions of publicly traded companies. In addition to investigating the merits of alleged misconduct, Casselle offers strategic direction to help clients anticipate and mitigate regulatory exposure, develop remediation plans, and strengthen their compliance programs.

A significant aspect of Casselle’s practice involves representing public companies and senior executives in connection with SEC investigations – including recent matters concerning cybersecurity intrusions, SPAC mergers, initial public offerings, and off-channel communications. Casselle also has extensive experience representing major broker-dealers and investment advisers in regulatory investigations involving all facets of their respective operational footprints — including matters arising from routine regulatory exams and more targeted investigations triggered by acute concerns of customer harm.

Casselle is a graduate of Harvard Law School, where she served as president and chaired the governing board of the Harvard Legal Aid Bureau — the nation’s oldest student-run legal services center, and one of the law school’s three historic honors societies. Previously, Casselle was an investigator for the Public Defender Service for the District of Columbia.

• Defended a multinational IT and consulting services provider in a years-long SEC investigation involving allegations of fraud, false filings, and disclosure control violations in connection with the SolarWinds cyberattack and related cybersecurity incidents reportedly perpetrated by threat actors working at the direction of the Russian Federation.
• Representing the former CEO of a development-stage, precision medicine company in an SEC investigation into allegedly false and misleading statements it made, around the time of its initial public offering, about the efficacy and commercial viability of its pipeline cancer drug.
• Represented a provider of vehicle electrification solutions for North American commercial fleets in an SEC investigation alleging violations of certain antifraud, proxy, and reporting provisions of the federal securities laws related to its SPAC merger.
• Representing a multinational investment bank in connection with an SEC probe into initial public offering syndicate practices.
• Conducting an internal investigation on behalf of a national financial advisory firm relating to assess and address issues stemming from the firm’s alleged breach of fiduciary duty and failure to monitor its employee retirement plan.
• Conducted an internal investigation on behalf a large financial institution, with more than $15 billion in assets, involving concerns of fraud and embezzlement by its chief information officer. Provided compliance counseling to address system and process flaws that allowed the alleged misconduct to previously go undetected, as well as regulatory counsel germane to certain self-reporting requirements.
• Directed an enterprisewide information security and cybersecurity assessment for one of the nation’s leading payment processing and check printing companies to assess its capabilities in light of the SEC’s new cybersecurity rules.
• Conducted a high-speed internal investigation on behalf of the audit committee of a multinational media company involving credible allegations of internal audit and compliance failures, securities fraud, and self-dealing spanning several years and implicating both the chief executive officer and the chairman of the board.
• Defended a major clearing firm in a multiyear investigation brought by FINRA’s Office of Market Regulation concerning its historic and ongoing failure to properly handle options orders placed on behalf of its institutional and retail clients.
• Defended a national broker-dealer in connection with FINRA’s investigation of alleged failures by the firm to adopt and implement sufficient account maintenance and estate processing procedures – implicating (among other things) the firm’s ability to detect and prevent elder abuse and exploitation.
• Represented a publicly traded media company in connection with parallel investigations by the Securities & Exchange Commission (SEC) and U.S. Department of Justice (DOJ) involving criminal fraud allegations and violations of other federal securities laws.
• Routinely represents senior executives, traders, financial advisors, and other associated persons in connection with enforcement actions brought by FINRA and the SEC — involving issues such as insider trading, unauthorized use of off-channel communications, registration issues, and sales practice violations.

• Chambers USA: Litigation: White-Collar Crime & Government Investigations, North Carolina, “Up & Coming” (2025)
• Best Lawyers in America®: Ones to Watch: Corporate Governance and Compliance Law (2024-2025), Criminal Defense: White Collar (2021-2025), Government Relations Practice (2022)
• Honors, Capital Pro Bono Honor Roll, D.C. Access to Justice Commission and the D.C. Bar Pro Bono Center (2024)
• Lawyers of Color Hot List, 2022
• National Black Lawyers: Top 40 Under 40, 2022
• Certificate for Pro Bono Service, Harvard Law School 2010
• Dean’s Scholar Prize, Harvard Law School, Spring 2010