SOUTH AMERICA : Publisher’s Missing Son Leaves Swirl of Mystery : Chile’s Cristian Edwards vanished Sept. 9. Speculation ranges from personal reasons to leftist terrorism.

SANTIAGO, Chile —  Cristian Edwards, the U.S.-educated son of Chile’s most powerful newspaper publisher, vanished without a trace on Sept. 9, and “el caso Edwards” remains a mystery today.

Some news media speculated early in the case that Edwards might have engineered his own disappearance for personal reasons. After exhaustive investigation, which has included help from the American FBI, authorities have said kidnaping is more likely, although they have offered no clue to who the abductors might be.

No political group has claimed responsibility, and no ransom demand has been made public. Still, there is no shortage of theories blaming leftist terrorists, former secret police agents or international gangsters.

Edwards, 33, is the son of Agustin Edwards, publisher of Santiago’s 91-year-old El Mercurio, the country’s most influential newspaper. The Edwards business empire also includes a chain of provincial newspapers, a major bank and other enterprises.

Cristian Edwards had been manager of the provincial newspapers since April, 1990. Before that, he worked in the United States for Pepsico, Inc., and General Reinsurance Corp.

He attended the private Choate School in Wallingford, Conn., then received a bachelor’s degree from Amherst College in 1979 and a master’s of business administration from the Wharton School at the University of Pennsylvania in 1985.

According to some published reports, Edwards had not adjusted well to life in Chile under his powerful father’s shadow. A quiet and orderly bachelor, Cristian lived alone in a three-bedroom house, making frequent calls to friends in the United States and sometimes flying there for visits.

Edwards was last seen by a janitor as he left his office after 9 p.m. on Sept. 9. A typed note found in the office the next day said he “was captive”--an unusual usage in Chilean Spanish--and that the abductors would get in touch with the victim’s father.

No further message or evidence of a kidnaping has been reported.

Analysts say that odd syntax and grammatical errors in the note indicate that it may have been written by someone who thinks in a foreign language. That has fueled speculation that Edwards faked a kidnaping to run away.

Other theories, favored by Chilean conservatives, say Edwards may have been kidnaped by one of three or four leftist guerrilla groups operating in this country. Abductors may be applying pressure for the release of “political prisoners,” or perhaps they have quietly “disappeared” Edwards in belated retaliation for the disappearances of hundreds of leftists under the military government of Gen. Augusto Pinochet, who ruled the country from 1973 to 1990.

Leftists favor theories blaming Edwards’ disappearance on former secret police agents accused of killings and torture under Pinochet. Under these theories, such men may be holding the publisher’s son as insurance against the conviction of retired Gen. Manuel Contreras, Pinochet’s former secret police chief.

According to another theory, an international criminal syndicate may have kidnaped Edwards for a multimillion-dollar ransom. But if the Edwards family has been negotiating a ransom, word has not leaked out.