James Forbes Chapin ( ) (July 23, 1919 – July 4, 2009) was an American jazz drummer and the author of popular texts on jazz drumming, the first two volumes of which are "Advanced Techniques for the Modern Drummer, Vol. I," and "Advanced Techniques for the Modern Drummer, Vol. II." (A third volume is planned.)
James Forbes Chapin was writing a book on drumming when he died. 
There isn't enough information to know whether Chapin was writing anything when he died. However the fact that a third book was planned may have fooled the system into thinking he was.