how did Gordon Arnold get into the parking lot?

Lee Bowers the railroad man says that the parking lot behind the Grassy Knoll was always locked. He says a police officer had leased it from the owner, and was sub-letting parking spaces only to those with keys. There was apparently an iron gate that had to opened (with a key) and moved out of the way.

And... Lee tells the story of the cars he saw driving around that day...

But Gordon Arnold doesn't even think twice about it. In his video interviews he says "well, there was a parade that day, and I wanted to see it, so I parked in the lot back there - (he points right behind him into the same parking lot) - and walked over to the corner because that's where I wanted to be".

What do we know about the condition of the parking lot on that day? Anything? Was the gate in fact locked, or was it open?