The authorities in San Mateo County in California are considering whether to file criminal charges in connection with the sale of a missing next-generation iPhone belonging to Apple.

The San Mateo district attorney could act by early next week, according to people involved in the investigation. The office has the option of filing felony charges.

According to California law, if property doesn’t exceed $950, a case will be classified as a misdemeanor, but since the technology blog Gizmodo paid $5,000 for the device, a felony charge would be possible.

On Monday photographs and video of a possible next-generation iPhone, which is expected to be announced in June,appeared on Gizmodo.com. After some speculation about the authenticity of the iPhone, Apple’s legal counsel sent Gizmodo a letter asking that the device be returned. The letter stated: “It has come to our attention that GIZMODO is currently in possession of a device that belongs to Apple.”

Brian Lam, Gizmodo’s editor, said the organization had returned the device and that Gizmodo “didn’t know this was stolen when we bought it.”

In a New York Times article on Tuesday, Nick Denton, chief executive of Gawker Media, which owns Gizmodo, explained over instant message that Gizmodo paid $5,000 for the phone.

According to people familiar with the investigation,  who would not speak on the record because of the potential legal case, charges would most likely be filed against the person or people who sold the prototype iPhone, and possibly the buyer.

Gaby Darbyshire, Gawker’s chief operating officer, said in an e-mail message Friday that the organization had not been contacted by law enforcement officials, and declined to speak further on any legal aspects. Apple also declined to comment.

Stephen Wagstaffe, San Mateo County’s chief deputy district attorney, explained that “if there is any case that arises out of our office at this point the police have not submitted for prosecution.” He added: “We certainly know about what happened here in Redwood City” regarding the missing iPhone, “and we are the jurisdiction for any legal prosecutions” that could come out of the episode.

California law prohibits the sale of stolen goods and states that a person who uses someone else’s lost property without permission may be guilty of theft.

Mr. Wagstaffe said in cases like this it might not necessarily be a matter of lost versus stolen. In some instances of missing property, he said, “we call it misappropriation of lost property; it’s a crime but it’s not theft.” He added that “knowledge is a very important factor in a theft case.”

CNet reported on Friday that a task force, the Rapid Enforcement Allied Computer Team, had been investigating the case.

According to its Web site, the group is a computer task force made up of “17 local, state, and federal agencies, with the Santa Clara County District Attorney’s Office designated as the lead agency.” The purpose of the organization is to “arrest and prosecute a wide range of criminal offenders” related to high-tech business.

When Firemint, the creators of the popular iPhone air-traffic-control simulator Flight Control, began working on a version of the game for the iPad, the company decided to move beyond the tablet’s roomy screen and into the third dimension.

The new version is called Flight Control HD and available now in the Apple App Store includes a new airfield that looks best if you are wearing a pair of red-and-blue anaglyph 3-D glasses.

However, players eager to experience the new multidimensional airfield will have to pick-up their own set of 3-D viewing glasses, said Alexandra Peters, community manager at Firemint.

“It’s more of a quirky surprise more than a big selling feature,” she said. “They’re the low-tech glasses so they are easy to find on Amazon.”

The iPad version, which costs $4.99 to download, allows two players to do battle with one another on a split screen. Players can also play against each other using multiple devices, including iPads, iPhones and iPod Touches, over a Wi-Fi network or Bluetooth.

Firemint, which is based in Melbourne, Australia, has posted a preview video on YouTube, though it doesn’t show the 3-D airfield.