Larry was a technical advisor/science advisor on films such as The Brain from Planet Arous, The Atomic Kid, The Magnetic Monster, and Zombies of the Stratosphere. At the time I contacted him, he was one of only two people involved with the making of Zombies who were still with us. The other was Leonard Nimoy. Mr. Cassingham passed away on 23 December 2007.
Larry's website - This website was created by his son Curt, and is a very good resource on the Cassingham family.