accessory[]
Panzram was a accesory to killing of Henry Minto in 1915
http://www.odmp.org/officer/9412-superintendent-harry-p-minto
There is also the possiblity that Panzram did not confess to all the murders that he claimed to commit-in footnotes of book "Killer" there are two referenes to murders in New england for which Panzram could have been the suspect-yet no proof.