Electrum binary files are being signed by three different developers as of the last year or so.  Check this guide for more information:
[GUIDE] How to Safely Download and Verify Electrum [Guide]

The developers' GPG signing keys can be found here: https://github.com/spesmilo/electrum/tree/master/pubkeys

The three developers signing current releases are Thomas Voegtlin (ThomasV,) Steven Oeste (Emzy,) and SomberNight/ghost43.