The HSCA investigation was pretty much a joke. The official finding was that Oswald fired 3 shots. The 2nd and 3rd shots hit JFK,with the 3rd shot being the fatal one.The HSCA AGREED with the single bullet theory,but stated that it happened during a different time frame than the WC report.

Then in the same report,the HSCA states that a probable 2nd gunman firing from the Grassy Knoll was responsible for a possible 4th shot.The sole evidence they cited for this was a later discredited Dictabelt recording made from a Dallas PD motorcycle cop's bike microphone.

Then,in their official conclusion,these nitwits state that the alleged conspiracy DID NOT involve any of the following:
The Soviets
Castro or his people
Anti-Castro people
The "Mafia"
Secret Service
FBI
CIA

So basically the HSCA found that there was a conspiracy to kill JFK,but somehow the conspiracy didn't consist of any actual people.