It has yet to be determinded when Casey borrowed the shovel because when the neighbor contacted LE after hearing that Caylee was missing, the neighbor could not remember the date the shovel was borrowed.
Greta from OTR, is reporting the shovel being taken on June 18th. This is just Mark Furhman's theory and he clearly reported when speaking to the neighbor about the shovel "the day has yet to be determined."
Mark used the 18th of June JUST to tighten up the time-line based on the June 16 and 17th numerous phone calls to her parents and others and the time of the calls.
I don't have a problem when Greta or Mark reports on the shovel as long as it starts out as : "Based on Mark's theory of closing in the time-line, we feel the shovel was borrowed on the 18th."
People are grasping at dates and rely on accurate facts. People are more apt to accept "theories" for things to make more sense.