Here's some likely suspects. "A" uses an lee enfield rifle which was the murder weapon but the bullet came from the back not the front. "B" is not yet introduced but Jack says he saw a "short gnome. Malnutritioned gnome". "C" had sick fantasies and desires but showed no interest in acting upon them. "D" has not yet been introduced but is the main bad guy, but, witness testimony says they saw a short malnutritioned gnome not a fat man.
making theories for lazy fans.