An extract from an article in The Australian 18 May that came via The Washington Post.
An article in the Annals of Applied Statistics claimed that the bullet evidence used to rule out a second assassin is fundamentally flawed. This research re-analysis involved new statistical calculations and a modern chemical analysis from the same batch Oswald is said to have used.
There was no conclusion about whether more than one gunman was involved but the researchers urged that authorities conduct a new and complete forensic re-analysis of the five bullet fragments left from the assassination. The bullet analysis presented to the House Select Committee on Assassinations supported the conclusion that only one shooter, Oswald, fired the shots that killed JFK. But the researchers disagree that the fragments came from just two bullets (supposedly) fired from Oswald's gun.