May 28, 2026 – LAS VEGAS, NV – The owner of a security company pled guilty on Wednesday to embezzling over $26 million from his girlfriend’s employer and purchasing high-end merchandise using the stolen funds and selling those items through an online consignment company.

According to court documents and statements made in court, from January 1, 2018 to February 28, 2025, William Keolanui Costa and his girlfriend, co-defendant Cynthia Marie Marabella, devised a scheme to defraud Marabella’s employer where she was employed as a controller at a Las Vegas-based construction company. As part of the scheme, Costa and Marabella fraudulently duplicated bonus checks and deposited the checks into bank accounts controlled by Marabella and Costa; opened credit cards in other peoples’ names and made unauthorized charges then paid the credit cards’ bills with stolen funds; provided false accounting records to the employer; created forged and false bank statements; and sent fictitious invoices from merchant accounts then paid the invoices with stolen funds.

Costa and Marabella used the stolen money to pay off vehicles, living expenses, and credit cards. They also purchased high-end merchandise with the stolen funds, such as expensive purses, shoes, clothing, and jewelry. Marabella sold the merchandise through an online consignment company. They received more than $245,000 from the sales. As a result of the fraud scheme, Costa and Marabella obtained more than $26 million from the employer.

“Stealing more than 26 million dollars through forged checks, fraudulent credit cards, and fabricated invoices is a deliberate and calculated financial attack against an employer,” said IRS Criminal Investigation (IRS-CI) Phoenix Field Office Acting Special Agent in Charge Scott Brown. “This criminal activity was not a mere lapse in judgment. It was a years‑long scheme built to siphon money, falsify records, and conceal the truth. IRS‑CI Phoenix will aggressively pursue anyone who uses deception and access to procure ill-gotten funds, and today’s plea makes clear that large‑scale financial fraud will be met with justice.”

In April 2026, Marabella pleaded guilty to one count of wire fraud and one count of monetary transactions in criminally derived property. Sentencing has been set for August 4, 2026.

Costa pleaded guilty to one count of wire fraud and one count of monetary transactions in criminally derived property. Sentencing has been set for September 2, 2026, before United States District Judge Andrew P. Gordon. The total maximum statutory penalty is 30 years in prison. A federal district court judge will determine any sentence after considering the U.S. Sentencing Guidelines and other statutory factors.

First Assistant United States Attorney Sigal Chattah for the District of Nevada and IRS Criminal Investigation Phoenix Field Office Acting Special Agent in Charge Scott Brown made the announcement.

This case was investigated by IRS Criminal Investigation and the Henderson Police Department. Assistant United States Attorney Kimberly Frayn is prosecuting the case.

Source: DOJ Release