The problem with chloroform, as with potassium cyanide and carbon tetrachloride, is that these poisons freeze the butterfly's muscles into an extreme version of rigor mortis, and the wings cannot be spread.

NPR: Excerpt: 'At Large and At Small'

Rigor mortis, a stiffening of the limbs of a corpse, begins around three hours after death, peaks at around 12 hours and is completely dissipated some two days later.

BBC: Syria crisis: 'Bodies of executed men' found in Aleppo

He had rigor mortis and was pronounced dead at the scene.

FORBES: Magazine Article

The bodies were caked in mud and showed signs of rigor mortis.

BBC: Syria crisis: Brahimi warns horror is 'unprecedented'

The bodies were caked in grey mud and showed signs of rigor mortis.

BBC: Syria crisis: 'Bodies of executed men' found in Aleppo