External Hard Drive last used / files copied on another computer? I have an external hard drive (called SEAGATE Expansion Portable Drive) and I was wondering if there is any way I can tell whether this hard drive has been plugged into another computer any time in the past month? 

It went missing and then turned up again. I would like to check whether it has been plugged into another laptop and had any files copied without my knowing - is there any way I can check this??

Thanks!
In short, No.
There's no way to be absolutely certain.

Files could have been copied from it, the entire drive could have been cloned without leaving a trace.  

You can have a look at the Last Opened data, but it's not conclusive proof of a negative.
You'd have to check a folder at a time [Search ought to be able to do it, but it never seems to work properly other than on "This Mac" which would show you too much other data]  

Open a folder on the drive, set it to View > As List.
Right click the columns bar at the top &amp; add Date Last Opened.

Click the new column to sort on it.
Check folder by folder...



Of course, anything you have opened since will confuse the results.