Unfortunately, due to the nature of Bitcoin, those coins are gone. There is no way to recover them... and very little chance of identifying the thief
Are you 100% sure you downloaded from electrum.org and NOT from one of the scam clone sites like "electrumsource.org"?
The clone sites, look pretty much IDENTICAL to the official site... you mention Electrum 3.0... which makes me think you might have the scam wallet... as it is showing "Latest release: Electrum-3.0"... however the OFFICIAL site has: "Latest release: Electrum-3.0.3" (and 3.0.3 has been out for weeks)
Just as a headsup the SHA256 checksum for the SCAM wallet is:
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Checksum information
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Name: electrum-3.0.0-portable.exe
Size: 21793360 bytes (20 MB)
SHA256: 2F3E48A85FDC8285F4C90DB4B7E817A654C85427941779186D87708FA6374E2B
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The OFFICIAL wallet shows:
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Checksum information
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Name: electrum-3.0.3-portable.exe
Size: 18485159 bytes (17 MB)
SHA256: EF5F4BCBB19901BEBCA743323AE7AF48FC349837FCF6A09F9A861C18FF8DBE13
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However, it should be noted that the ONLY true way to tell if you downloaded the correct client is to check the digital signature of the downloaded installer file and make sure that it was signed by ThomasV.
Checking sig on scam wallet shows:
Checking sig on OFFICIAL wallet shows: