However, court documents do not detail any specific incidents allegedly committed by Elmas at the other two financial institutions.

"Basically, Elmas stole from clients while at the other institutions but not from those institutions themselves," Joshua Stueve, a public information officer for the U.S. Attorney's Office in Alexandria, said.  "The businesses [either the financial institutions or an insurer] have since repaid the victims, therefore incurring loss and becoming victims themselves."

Stueve said he did not have exact breakdowns as to the totals from clients at each institution. He also noted that Elmas' employment history was not in the public record, though clearly his employment history with Apple FCU was.

Naval Research Lab FCU and Raymond James Financial Services did not return an email and phone message Tuesday seeking comment about their involvement in this case.

Nonetheless, while working as an investment adviser at Apple Financial Services, an affiliate of Apple FCU, Elmas deposited his clients' funds in an account that he controlled at the $63 billion Navy Federal Credit Union in Vienna, Va., according to court documents.

The account was named I.E. Financial Solutions. Elmas falsely described it to clients as an investment vehicle such as a CD or real estate investment trust.

Read more: Many victims were elderly or widowed…

Over the years, he stole nearly $3 million from at least 20 credit union members, many of whom were elderly or widowed and often entirely dependent on this money during their retirement years for monthly income, U.S. Assistant Attorney Chad I. Golder, said in court documents.

Elmas lost about half of the $3 million in stock trading.

"Indeed, although some businesses or financial institutions are now left holding the bag, it is significant that [unlike many fraud cases] Elmas stole from regular people," Golder said. "In fact, he often had to look these very people in the eye and lie to them, despite knowing they were vulnerable and entirely dependent on his advice for the financial security of their retirement and children. The consequences of his actions [have] been devastating for his victims, as they explain in the letter they have written to the court."

In court documents, some members said they considered Elmas a friend who they not only trusted but also respected and admired.

"Our concern today, as it has been the entire time, has been replenishing and actively working to make our members who were affected by this case whole," Robert Sowell Sr., vice president of community relations for Apple FCU, said.

Sowell also said 16 credit union members have been made whole and Apple FCU is actively working to resolve the remaining four cases.

Elma's lawyer, David G. Barger of McLean, Va., said his client has accepted responsibility for his crime and has cooperated with authorities, victims, Apple Financial Services, CUNA, CUSO Financial Services in San Diego, Calif. and others.

In court documents, Barger said Elmas continues to be cooperative and has agreed to liquidate every asset he owns, including his retirement account, 401(k), pension fund and all of his financial accounts.

Barger acknowledged Elmas lost about half of the $3 million in stock trading in an effort to dig out of the hole he had dug.

"Instead, he simply dug it deeper," Barger said in court documents. "A substantial amount of funds were returned to clients during the course of the offense. Some of the funds admittedly were used for his own benefit."

Barger said Apple Financial Services and insurers have repaid the vast majority of victims. The rest of the victims are in the process of negotiating repayment with Apple Financial and insurers.

"Apple Federal Credit Union is to be commended for their diligence and efforts in pursuing their investigation into the conduct [of Elmas] and their efforts in restitution," Barger said.

In court documents, Elmas wrote that he has recognized the pain he has caused and is heartsick about it.

"I will continue to do what I can to help lessen the loss, and to show that I am trying to rehabilitate myself," he wrote. "I apologize and hope there will be some measure of forgiveness someday."