Complex sentence: Media interest in the group began in 1997, when parallels were drawn between the GCCA, then known as the Aquarian Concepts Community, and the Heaven's Gate sect, the group led by Marshall Applewhite, which is notorious for its 1997 cult suicide.
Split into simpler sentences: Media interest in the group began in 1997, when parallels between the GCCA, then known as the Aquarian Concepts Community, and the sect Heaven's Gate were drawn. That group led by Marshall Applewhite, is notorious for its 1997 cult suicide.