This whodunit begins on a beach in Mississippi, where a bottlenose dolphin turned up dead one day this spring.

A man found the animal lying at the water’s edge in April and called the Institute for Marine Mammal Studies, which responds to dolphin strandings and conducts necropsies, or animal autopsies, said Moby Solangi, the organization’s executive director.

Since there was no visible sign of foul play, the remains weren’t examined immediately.

But in July, veterinarians dissected the dolphin and found something was amiss: a bullet, lodged in the animal’s lung. The dolphin had been shot to death, and in an added blow, the necropsy revealed that she had been pregnant with a full-term calf, which also died.

Now, a $11,500 reward is being offered to help solve the case. It’s the latest example of violence against dolphins in the northern Gulf of Mexico, which experts say is becoming increasingly common.