Complex sentence: Chevalier had experimented with explosives in a hangar and was suspected of making a bomb to dispatch Napoleon, however, the machine infernale that exploded a month later in the Rue Saint-Nicaise was not Chevalier's bomb.
Split into simpler sentences: Chevalier had experimented with explosives in a hangar and was suspected of making a bomb to dispatch Napoleon. The machine infernale that exploded a month later in the Rue Saint-Nicaise was not Chevalier's bomb.