iPhone 6, deleted pictures and it still says they're taking up 4GB of space
I moved the pictures from my wife's iPhone 6 off the phone and on to our computer. But under the Usage area it still says that they're taking up 4.1GB of space; yet there aren't any pictures left on the device. How do I fix this problem? It's caused issues saying that the device is low on storage.
iPhone 6, iOS 8.2