Lenny Stogel was one of The Cowsills managers. He was a HUGE part of getting them their first recording contract and saving Halidon Hall for them. Lenny died in the plane crash of Flight 191 a DC-10 on a run from Chicago to Los Angeles on May 25, 1979.
Some newspaper articles regarding the accident:
Diverse Travelers Meet With Tragedy
Victim's Parent Died In Earlier 'Worst Ever' Crash