How can we still find the device if its offline?
If it is offline you cannot locate it electronically. The following link has information on steps you can take that will take effect if it does come back online: If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
You can't. It must be on and connected to the Internet using Wi-Fi.
If Your iDevice Is Lost Or Stolen
If you activated Find My Phone before it was lost or stolen, you can track it only when it is connected to the Internet by Wi-Fi or cellular. What you cannot do is track your device using a serial number or other identifying numbers. Neither Apple nor anyone else can find your device. You cannot recover your loss unless you ensure your device for such loss. It is not covered by your warranty.
If your iPhone, iPod, iPod Touch, or iPad is lost or stolen what do you do? There are things you should have done in advance - before you lost it or it was stolen - and some things to do after the fact. Here are some suggestions:
1. Reporting a lost or stolen Apple product
3. AT&T. Sprint, and Verizon can block stolen phones/tablets
4. What-To-Do-When-Iphone-Is-Stolen
6. What to do if your iOS device is lost or stolen
7. 6 Ways to Track and Recover Your Lost/Stolen iPhone
9. Report Stolen iPad | Stolen Lost Found Online
It pays to be proactive by following the advice on using Find My Phone before you lose your device:
2. Setup your iDevice on iCloud
3. OS X Lion/Mountain Lion- About Find My Mac
4. How To Set Up Free Find Your iPhone (Even on Unsupported Devices)
One of our devices got stolen and its offline. How can we still find it?
