iPhoto preference to "copy imported items to the iPhoto library" was unchecked.
If that is the case then as you said in your first post the originals are most likely gone.
The best you can do now is to get the thumbs out of the iPhoto library package.
Before proceding I'd make a backup of the iPhoto library as if this goes you'll really lose everything.
Once you have the library backed up you can select it in Finder and use Show Package Contents to open it. Once opened you can go into the Thumbnails folder. In there will be the thumbs from the library. You can copy them out or create a new iPhoto library and import them into the new library.
Note that checking it does not change the past magically - it only changes from the moment you checked it forward
Also not that is is strongly recommended that you do not uncheck that preference - one of the many reasons it tha tit makes upgrading or replacing defective hardware much more difficult
Where are your original photos?
Since you were running a Referenced library and the source files were stored on the external hard drive that crashed and was replaces you have no way to recover your photos.
If you still have the crashed EHD you might be able to get someone to try recovery procedures on it to tryh to recover your photos. But it won't be cheap.