Five bald eagles and a fox found dead on a Maryland farm more than a year ago died of poisoning, according to federal officials.

The animals were found in January 2017 on a farm in Easton, Md. The new revelations about how they died came after radio station 1430 WNAV in Annapolis filed a Freedom of Information of Act request with the U.S. Fish and Wildlife Service for details in the case.

The animals were killed by ingesting carbofuran, the same banned pesticide said to have killed 13 bald eagles found in 2016 at another farm in Federalsburg, Md.

According to an article on WNAV, pathology reports found that the eagles and fox found dead in Easton “died of carbamate intoxication.” It went on to say, “Carbofuran was detected in the upper gastrointestinal tracts of all the animals.”

There have been several incidents in recent years in Maryland of bald eagles being found dead.

One instance that gained national attention was at the 100-acre farm in Federalsburg where 13 bald eagles were found dead. It was one of the largest single die-offs of bald eagles in Maryland in recent decades. In another case, five bald eagles were poisoned in Delaware in 2016.

Finding out who poisoned the birds could be difficult. Authorities in the Federalsburg case sent the birds’ carcasses to a specialized lab in Oregon for analysis, and a $25,000 reward was offered. But officials ultimately said they did not have enough evidence to charge and prosecute anyone.

It is illegal to use carbofuran, but eagle experts said that even though stores are banned from selling the pesticide, some people still have it stored and use it later to kill rodents or other unwanted pests. Once an animal dies, the eagles — which are scavengers — eat their carcasses and become ill.

That appears to be the case in the Easton deaths. According to WNAV, experts found that most of the bald eagles had carbofuran in their stomachs.

Carbofuran is considered to be a highly toxic pesticide. It is particularly harmful to birds and is banned by the Environmental Protection Agency. Small pieces of carbofuran may look like grain seeds to birds.

In the case of the Easton animals, the Fish and Wildlife report said “fox tissue” was found in the food that the eagles had ingested, so they likely ate the fox that had also eaten the poison. Experts said the fox probably ate the poison and then could have traveled away from that area before it fell ill. The Fish and Wildlife Service said no poison was seen at the farm where the dead animals were found, according to WNAV.

Carbofuran came under harsh criticism 30 years ago after it was said to have killed as many as 2 million birds a year, according to federal experts. That came at a time when bald eagles were struggling as a population. The granular form of carbofuran was banned in the mid-1990s.

Bald eagles have made a comeback and are protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act.

There have been several cases of people being fined for killing animals after they scavenged a poisoned carcass. In one case, a Wisconsin father and son had to pay a fine of more than $100,000 after killing more than 70 wild animals, including some bald eagles. They had said they were trying to use carbofuran to get coyotes and wolves.

The toxin causes excessive salivation, diarrhea, seizures and vomiting. It can also lead to glands in the lungs secreting fluids and, as one toxicology expert said, causes animals to “drown in their own fluids.” One official with the Fish and Wildlife Service has said there is an “epidemic on the Eastern Shore” of wildlife-poisoning crimes.