There was. Oswald didn't cover his tracks. An open and shut case against him was developed before the weekend was over.
"I have not read that much about the 1979 Commission Report, but it was my understanding that Blakey the head counsel dominated the commission. His presumption was the Mafia was involved and spent a lot of time and resources with following that presumption and then when time and money was running out attempted to do some hocus pocus with the audio much like Arlen Specter did with the magic bullet."
Mostly true. The committee almost entirely confirmed the Warren Commission findings, and tested all the conspiracy theories people were promoting, and still promote, and found them false.
But at the very end, some analysts claimed to find audio proof of a shot from the grassy knoll.
"It is a shame really as it was only 15 years after the murder and a proper investigation could have thrown new light on the events."
It was a very thorough investigation. It settled a lot of the questions that had been raised up till that time. It was only the audio business at the end that messed it up.
In America the accused have the right to remain silent as well as the right to speak in their defense.
Is there any electronic record or even a written record of notes taken during the twelve hours Oswald was interrogated?
You are exactly right the case was closed and the cover-up complete in less than 48 hours after Oswald was arrested.
A self-proclaimed patsy was accused, tracked down, arrested, arraigned, convicted, and executed.
The best cover-up is a frame job.
The best frame job is when the guy framed is dead.
That is the beauty of the recent attempt on Trump.
The twenty year old dietary assistant at a nursing home was both a shooter and a patsy.
He was a dead man shooting as he was scoped by counter snipers who allowed to get off eight shots before he was forever silenced.
Blakey now says it was a conspiracy & they had more than just the audio info. So no, it was just not the audio info.