Santa Barbara hedge fund owner Michael Klein, his daughter and her friend remained missing Tuesday after their small plane disappeared in a rugged area of Panama over the weekend.

Klein, 37, chief executive officer of Pacificor LLC of Santa Barbara; his 13-year-old daughter, Talia, and her 12-year-old friend, Francesca “Frankie” Lewis; and pilot Edwin Lasso were on a 45-minute flight to Volcan, a mountainous coffee-growing region in western Panama, when their Cessna 172 vanished from radar around noon Sunday. The flight originated on Isla Secas, an island Klein owns in the Gulf of Chiriqui.

Family friends said Klein and the girls were expected to return to Santa Barbara on Christmas eve after a holiday weekend on Isla Secas. Both girls are seventh-graders at Crane Country Day School.

A $25,000 reward has been offered for information leading to the discovery of the plane and those aboard. News reports said about 60 rescuers, including members of Panama’s national police and civil defense agency, are searching for the aircraft on the ground. Four helicopters and two planes also are involved in the search.

Initial search attempts were hampered by poor communication systems and bad weather, including fog and heavy rains.

Klein, who graduated from UCSB at age 17, started MIBEK Corp., a developer of financial analysis software that he sold in 1992. He then founded Transoft Networks Inc., a leading supplier of storage area networking software that Hewlett Packard purchased in 1999, according to the Pacificor Web site.

He then became president and chief executive officer of eGroups Inc., the world’s largest group e-mail communication service. Yahoo! Inc. acquired eGroups for $450 million in 2000. Now known as Yahoo! Groups, the service has more than 100 million users globally, Pacificor’s Web site says.

Klein became Pacificor’s largest investor in 1999, was elevated to CEO and president in 2001, and acquired the firm outright in 2002. He also acts as its chief investment officer, the Web site says.