While police initially were investigating the case as a possible suicide, it now appears Nadel did not go through with it. In a statement provided to CNBC by Nadel's stepson, Geoff Quisenberry, the family says, "We love him very much and would like him to come home." And a business partner, Neil Moody, told Reuters: "At this point we have every reason to believe that he is (alive)."
Video Update: Monday's developments in the case.
The Securities and Exchange Commission is now investigating where the $350 million went. In their statement, Nadel family members say that they, too, "have been victimized by his unauthorized actions," CNBC has learned.
Nadel is the general partner for Scoop Management, which operates three hedge funds. He also manages the assets for the Viking and Valhalla funds, for which Moody serves as general partner. The companies share a single office in Sarasota.
Here is the full statement from Scoop Management issued late Saturday to CNBC:
"The employees of Scoop Management, which includes Peg Nadel, the wife of Arthur Nadel, have just learned that they along with many others who invested money with Art have been victimized by his unauthorized actions. We are cooperating with all the appropriate authorities, and are in the process of gathering facts. We are also very focused on attempting to find our husband and father and employer to assure him that we love him very much and would like him to come home."
According to a police report, Nadel had phoned his stepson on Wednesday, distraught. He told him to "come over and read a note," apparently a suicide note. While it now appears Nadel did not follow through, his exact wherabouts are not known.
The Sarasota County Sherrif's Department confirmed to CNBC that they found Nadel's car Thursday afternoon at the Sarasota-Bradenton Airport. It was not immediately clear if Nadel has his passport.
Arthur and Peg Nadel are prominent members of Sarasota society, raising funds for organizations including the Sarasota Opera, Jewish Family and Children's Services, and Habitat for Humanity.