The story I heard goes like this. Electra first sued Trek in 2011 over over the patent infringement of the Electra Townie by the Trek Pure:

Electra Files Lawsuit Against Trek; Cites Patent Infringement
(https://bikerumor.com/2011/01/26/ele...-infringement/)

Then a few years later in 2014, Trek purchased Electra:

Didn’t See That Coming- Trek Acquires Electra Bicycle Company
(https://bikerumor.com/2014/01/06/did...cycle-company/)

There may be far more to it than I am privy to, but the rumor on the ground here in Wisconsin was that it wasn't looking good for Trek legally and that purchasing Electra outright was cheaper than settling. It seemed to be an amiable acquisition, but like almost all Trek acquisitions, all the interesting stuff eventually falls out of the catalog. Perhaps someone else will have more information.