The departure of Nancy Heinen, Apple Computer Inc.’s general counsel, seems to be the latest top secret at a company that really likes its secrets.

Almost a week after news site AppleInsider first revealed the company’s nine-year GC had left the company, it remains unclear whether one of Silicon Valley’s highest-ranking female attorneys was forced to leave or whether she had resigned � or even when her last day was.

Heinen answered her cell phone Wednesday while hiking the hills near her Portola Valley home, but did little more than confirm she would not be returning to the Cupertino-based company.

When asked what her future plans were, Heinen replied, “I’m hiking � that’s my plan for today,” before declining to provide further information.

Apple, notoriously tight-lipped about executive departures � and pretty much everything else � was equally mum.

Apple spokesman Steve Dowling confirmed that Heinen was “no longer an Apple employee,” but declined to say when she had left or why. An Apple employee who requested anonymity confirmed that Heinen’s last day was May 1.

Apple Chief Financial Officer Peter Oppenheimer will serve as interim GC while the company launches a search for a permanent replacement, Dowling said.

Few interviewed for this story wanted to comment on the record about Heinen’s departure.

One legal recruiter said that Heinen had an “unusually strong relationship with [Apple CEO] Steve Jobs,” and added that it was highly unlikely Jobs would have fired Heinen. At the same time, the mystery with which Apple has shrouded the matter has raised some eyebrows. “Something big must be happening” if Apple was being so quiet about the matter, the source said.

Others say this is typical Apple behavior. “They’re extremely tight-lipped over there,” one Bay Area general counsel said. “They try to muzzle leaks. � they really want to control the message [going] out. It’s going to be pretty hard to get any sort of scoop out of them.”

Before joining Apple as its GC, Heinen was vice president, general counsel and secretary of the board of directors at NeXT Software Inc. until its acquisition by Apple in 1997.

She has a sterling reputation as one of Silicon Valley’s best lawyers. Fenwick & West Chairman Gordon Davidson, who started out with Heinen as an associate in a small Palo Alto high-tech boutique, said he had “nothing but great things to say” about her.

“She’s a fantastic lawyer and a great person,” he said. Fenwick IP chairman David Hayes, who represents Apple in intellectual property matters, was not available for comment.

Alan Mendelson, co-chair of Latham & Watkins’ venture and technology group, played down the lack of information about Heinen’s move. “You never know in these kinds of situations,” he said. “I wouldn’t make too much of that.” He added that Heinen, whom he has known for years, was a “terrific lawyer and a “tremendous asset” to Apple.

Heinen’s departure came just days before Apple secured a significant win in its fight against Apple Corps, which was created by the Beatles in 1968 to oversee the rock band’s business interests. A London court ruled Monday that the computer company’s apple logo did not violate a non-compete agreement with Apple Corps.

During her tenure at Apple, Heinen has had to deal with a number of complicated licensing agreement issues, adding music videos and TV shows to its extensive music catalog. Apple has also dealt with patent suits and charges that iPods cause hearing loss.

In May, Apple successfully sidestepped a threat by France to force the computer company to make songs sold through iTunes available to devices that compete with the iPod.

Heinen is one of three high-level Apple executives to leave the company since March. Chief software technology officer Avadis Tevanian Jr. and senior vice president of Apple’s iPod division Jon Rubinstein left the company in March. All three were originally brought on board at the same time when Apple acquired NeXT.

Tevanian, who has since joined the board of directors at voice application company Tellme Networks Inc., declined to comment on Heinen’s departure.

Apple wouldn’t comment on the size or structure of its legal department. According to a Corporate Legal Times August 2005 report, Apple has 43 in-house lawyers and placed 184th on the list of the country’s 200 largest legal departments, sandwiched between Albertson’s Inc. (45 lawyers) and Genentech Inc. (43 lawyers).