Mr. Raniere, 57, recently left the Albany area and traveled to Mexico, where Nxivm has hundreds of followers, to stay with an adherent in Monterrey. Former associates said Mr. Raniere had never previously gone to Mexico. A former Nxivm member in Mexico said that Mr. Raniere was seen recently in Monterrey, though his current whereabouts is not known.

Mr. Raniere and other Nxivm officials did not respond to requests for interviews or repeated emails. A lawyer who represents the group, Robert D. Crockett, also did not respond to written questions, including whether federal or state officials had contacted Nxivm.

In recent weeks, Nxivm’s leaders have posted statements on the website of Executive Success Programs, contending that the secret sorority was not connected to Nxivm and that Mr. Raniere was unaware of its practices.

Nxivm also stated that it has conducted an independent investigation of the sorority and determined that the women in it are healthy and happy.

”Our experts, a forensic psychiatrist of international repute, psychologists and ex-law enforcement say members of the sorority are thriving, healthy, happy, better off and haven’t been coerced,” Mr. Raniere said in a statement. The group did not name the experts.

Several former Nxivm members said that senior women in the group, including the daughter of its co-founder, were involved in the sorority and branding ceremonies. In addition, a text message sent by Mr. Raniere indicated that he was aware that women were being branded with a symbol that contained his initials.

“Not initially intended as my initials but they rearranged it slightly for tribute,” he wrote in that message. “(if it were abraham lincolns or bill gates initials no one would care.)”