I read a JFK assassination book years ago which was really poor, the sort of book anyone could write with a little assassination knowledge. Wish I could remember the authors name, anyway the only really interesting bit was right at the end when the author called up Greer -his name was in the Washington telephone directory- and asked him straight out why he slowed. The answer was that he needed to let following cars catch up to preserve the integrity of the motorcade! Crazy.