The sad news has been confirmed here, among other sources:
The composer George Russell, best known for his 1953 music theory The Lydian Chromatic Concept of Tonal Organization died yesterday aged 86. He had been unwell for some time and had been suffering from Alzheimer’s disease. His ideas were at the time seen as some of the first major contributions by a jazz musician in the field of music theory.
In the 1960s he moved to Scandinavia and taught in Sweden and in Denmark and thanks to Swedish radio was able to record his compositions and undertake new commissions. He worked with Don Cherry and a young Jan Garbarek and then on his return to the States joined the faculty of the New England Conservatory. Later in the 1980s and 90s he formed and toured his Anglo-American group the Living Time Orchestra which featured Andy Sheppard among the soloists. His albums include the classic 1961 Riverside album Ezz-Thetics.
avantmusicnews.com, Avant Music News, Jul 2009
I first heard Mr. Russell's music in the late Nineties, after picking up his excellent Stratus Seekers album with trumpeter Don Ellis, Dave Baker on trombone and tenorman Dave Young (among others). The arrangements were unique, solos burning, incredibly swinging but not like anything else I'd heard at the time. He had a great run on Decca and Riverside in the early Sixties, and his Scandinavian bands of the subsequent decade (late 60s-70s) were equally hot.
I don't pretend as a nonmusician to understand his theories, I just know that I've gotten a lot of joy out of his work. RIP, Mr. Russell, and thanks for all you gave.