At least 510 people from around the nation apparently have lost a total of $31 million to a Chattanooga foreign currencies trader who promised sky-high investment returns but now is believed by federal officials to have operated a classic scam.

Luis H. Rivas, meanwhile, is nowhere to be found as a U.S. Bankruptcy Court trustee scrambles to pinpoint the businessman’s assets amid concerns he may be trying to liquidate his accounts and flee the country.

A multistate federal criminal investigation also continues, since authorities said Mr. Rivas operated offices in Chattanooga, Spartanburg, S.C., Orlando and Tulsa, Okla. All have closed in recent months, and Mr. Rivas does not return phone calls, according to creditors and former employees.

FBI Agent Jim Lannamann of Spartanburg declined comment on the investigation but said no criminal charges have been filed.

“There’s no question this is a Ponzi scheme,” said Knoxville-based U.S. Bankruptcy Trustee Grey Steed, who was appointed Friday by U.S. Bankruptcy Judge John Cook to begin sifting through Mr. Rivas’ financial records.

Court records show Mr. Rivas probably was using money he received from new investors to pay promised monthly returns as high as 10 percent to those who invested before them, which is how such schemes work.

Mr. Steed said it appears that Mr. Rivas, who operated a company called The Forex Project on Century Oaks Drive in Chattanooga, took $31 million from investors over the last year but actually invested only $5 million in the foreign currencies market. Much of the money may have gone toward Mr. Rivas’ “lifestyle” and employees’ salaries, Mr. Steed said.

Testimony at the bankruptcy hearing Friday indicated Mr. Rivas had 40 employees in Chattanooga and a payroll of $200,000 a month.

Monday marked the deadline for Mr. Rivas to respond to a petition for involuntary bankruptcy, but he had not responded by Monday afternoon, according to the court file. Four out-of-state creditors filed the petition in mid-May claiming Mr. Rivas owed them a collective $1.1 million.

Judge Cook now must either deny or grant the petition, which would allow all creditors to begin to recover at least some of their investment amounts. To do so, they must file a standard claim form that can be obtained from any U.S. Bankruptcy Court. The form must be filed with the U.S. Bankruptcy Court clerk in Chattanooga.

But that’s only if any money is found.

Mr. Steed said he worked throughout the weekend to find Mr. Rivas’ assets but still has not been able to take possession of any of them.

Mr. Rivas promised investors as much as a guaranteed 5 percent monthly return on their investment amount — a whopping 60 percent annual return — but stopped paying those returns in February and March, court documents show.

In some instances, he took people’s money and paid no returns at all, according to court testimony, all the while claiming his investors could become rich by pouring their money into the foreign currencies market.