If, as you say, the doors "were probably secured" then it went against Dr. Penn's understanding that "the doors should have been locked because I gave the keys to the SS that morning at 7:30 so they should have been locked when you went through them at 10:30". The night before in Duluth security people told me there was no weak link in security in the campus arena where JFK spoke. 15 hours later in Grand Forks the security was full of holes. 45 years later, when I find Dr. Penn, he asks me after many hours of discussion about the assassination, "do you think i was involved in the plot on 9/25/63". He never expected to be discovered 45 years later. It is true that if the plotters knew the plot was called off by Nagell on 9/20/63 it didn't matter if doors were left open. However one feels about the veracity of the book "Farewell America", it does indicate the the plotters were on site that day in Grand Forks.