According to police, the 57-year-old man and two of his colleagues cooked and ate five bullfrogs they caught at a reservoir, at a restaurant in Daejeon, 164 kilometers south of Seoul, on March 9.
After the man had finished eating, he suddenly started to vomit and was taken to a nearby hospital as his condition worsened. He died early the next morning.
The man’s two colleagues showed similar symptoms, but not as severe.
Police found bufotenin, a toxic substance found mostly in toad skin which may cause death when ingested in large amounts, in the food remains.
Investigators believe the man ate toads thinking that they were bullfrogs.
“Toads are similar in shape to bullfrogs, but much care must be taken since it is dangerous to ingest as it is poisonous,” said the police.