CUPERTINO — An iPad “test model” was one of the items taken during a robbery and kidnapping at a Cupertino house earlier this month, according to the Santa Clara County Sheriff’s Office.

The sheriff’s office, which would not disclose more details about the stolen device, but said it has not been recovered.

It’s unclear whether the Apple item was related to an upcoming product release or was an outdated model or test device.

“We are still investigating everything about this case,” sheriff’s spokesman Sgt. James Jensen said.

The robbers took the device, along with electronics, prescription drugs and cash valued at $7,500, from a Cupertino home during an incident in which a 20-year-old man was kidnapped and robbed after answering a woman’s online advertisement.

Authorities on Tuesday said the victim told detectives that “a test model iPad from Apple” was taken along with the other items.

The Santa Clara County District Attorney’s Office has arrested Katherine Stump, 20, from Danville, and Alexander Nejat, 25, from Dublin on suspicion of four felonies, including kidnapping, first-degree robbery and making criminal threats. In the complaint, prosecutors allege one of them has a prior conviction for felony assault.

Nejat was already in custody in Alameda County after being arrested by Pleasanton police in a similar case. Stump was arrested in the same Pleasanton case, was released and then was re-arrested in connection with the Cupertino case.

Deputies say on April 5, a young man in his 20s contacted a female from an “online advertisement” and met the woman and a male associate two blocks away from his Cupertino house. They all drove to that house.

Once inside, Stump threatened the victim with a knife and Nejat pepper-sprayed him in the face, deputies said.

Stump and Nejat took the items and forced the victim into their car, driving him three-quarters of a mile from the house, then releasing him.

The victim didn’t contact the sheriff’s office until five days later.

When the sheriff’s office released a composite sketch of the suspects, a Pleasanton police detective identified them as the two people arrested in a similar case in his city.

When Pleasanton police arrested Stump and Nejat, the pair had several phones and computers, which Stocking said investigators believe belong to other victims who may be reluctant to come forward.

The theft of Apple products before their public release has caused Apple embarassment in the past. In the most famous case, an Apple engineer in early 2010 left an iPhone 4 prototype in a Redwood City bar, and the top-secret device was found by two Bay Area men who sold it to a Gizmodo blogger for $5,000. The men, Sage Wallower of Emeryville and Brian Hogan of Redwood City, eventually pleaded no contest to misdemeanor charges and were sentenced to one year of probation.

But the incident helped pull back the curtain on a notoriously secretive Apple after it was disclosed that then CEO Steve Jobs had personally called Gizmodo’s Jason Chen and told him: “Hi, this is Steve. I really want my phone back.”

Even after the phone was voluntarily returned to Apple, authorities conducted a controversial raid on Chen’s home in Fremont and Gizmodo was banned from Apple events for years.

“Any company that loses a valuable item will pull out all the resources they can to locate that item, whether it’s calling in a PI or using their own security people who are generally ex-cops,” said Chuck Wall, a private detective with Creative Security in San Jose. “If it’s really a prototype of some kind, Apple would obviously want to keep this secret and not have it available for another company to know about. They may not have a patent on it or may not want others to take it apart and copy features from it to use in their own products.”

But Wall said that here in Silicon Valley thefts of proprietary equipment is fairly common.

“It’s amazing how often these items turn up missing, and not just Apple,” he said. “I just had a company call me up to say their CFO was out to dinner and the product was in the back seat and the window got smashed and the thing was gone, which for them opened up all kinds of possible problems.”