Two Apple employees accompanied by police officers reportedly searched a San Francisco residence to get back the lost prototype of the potential iPhone 5.

San Francisco police confirmed last Friday that they had helped Apple investigators in a search for a "lost item," but they declined to disclose what exactly Apple had lost. But, the San Francisco Police Department’s press release about the search was named “iPhone5. doc”, which provide strong hint that the lost prototype is of the iPhone 5.

Apple investigators have so far failed in getting back the lost device.

In its statement, the police department revealed, “The two Apple employees met with the resident and then went into the house to look for the lost item. The Apple employees did not find the lost item and left the house.”

The prototype had gone missing in July this year.

It is the second time when the Cupertino, Calf.-based gadget maker has lost a prototype of the upcoming iPhone. Last year, the gadget maker had lost a prototype of the iPhone 4. At that time, tech blog Gizmodo purchased the prototype for $5,000 and published its photos when the device was still under development.