Robert F Kennedy Jr faces calls from environmentalists for an investigation over a historic claim that he once cut the head off a dead beached whale with a chainsaw to take it home on the roof of his vehicle.

A group that supports Kamala Harris for president says Mr Kennedy’s alleged removal and transportation of the skull of the whale may have broken the law.

Mr Kennedy, 70, has not commented on the incident, detailed by his daughter in an interview 12 years ago.

The call for an investigation comes days after he suspended his independent presidential campaign, which was marked by strange twists including his confession that he once dumped the body of a dead bear in New York’s Central Park.

Mr Kennedy has now endorsed Donald Trump for the presidency, and has been offered a place on the Republican candidate’s transition team if he is elected.

The incident with the whale’s head, which dates to around 1994, was recounted by Kathleen “Kick” Kennedy in a 2012 interview with Town & Country magazine.

Mr Kennedy, who is said to enjoy studying animal skulls and skeletons, reportedly heard that the dead animal had washed up in Hyannis Port, Massachusetts, where the family was staying.

He went to the beach to cut off the head with a chainsaw, and then proceeded to tie it to the roof of the family minivan with bungee cords. The family then drove back to their home in New York, Ms Kennedy said.

“Every time we accelerated on the highway, whale juice would pour into the windows of the car, and it was the rankest thing on the planet,” Ms Kennedy told the magazine.

“We all had plastic bags over our heads with mouth holes cut out, and people on the highway were giving us the finger, but that was just normal day-to-day stuff for us.”

The call for an investigation was made by the Center for Biological Diversity Action Fund, which has publicly endorsed Democratic candidate Kamala Harris for president.

The group wrote a letter to set out their case to marine protection officials at the National Oceanic and Atmospheric Administration (Noaa). The BBC has approached the Noaa for comment.

The letter, quoted by US media, said Mr Kennedy may have broken multiple federal laws by collecting wildlife body parts and transporting them across state lines.

“Vital research opportunities are lost when individuals scavenge a wildlife carcass and interfere with the work of scientists,” the group’s political director Brett Hartl wrote.

“This is particularly true of marine mammals, which are some of the most difficult wildlife species in the world to study,” Mr Hartl added.

Noaa is yet to publicly acknowledge receipt of the letter or issue a comment, and nor has Mr Kennedy. The BBC has approached his campaign for comment.

At one point earlier this year, Mr Kennedy averaged about 15% in presidential preference polls as an independent candidate.

His pitch blended anti-establishment and anti-corporate rhetoric with liberal social positions, environmentalism and controversial vaccine scepticism.

But his numbers dwindled, and he announced last week he was suspending his campaign.

Although he initially competed to win the Democratic nomination, he ended up criticising his former party and offering his endorsement to Donald Trump. The move dismayed his relatives, who are the most famous family in Democratic politics.

Mr Kennedy’s campaign attracted a range of bizarre and scandalous headlines.

In May, the New York Times ran an article revealing he had told lawyers involved in his 2012 divorce proceedings that he was suffering from a memory issue relating to a dead brain parasite.

In mid-July, Mr Kennedy texted an apology to a former family nanny after Vanity Fair magazine published a story in which she accused him of unwelcome sexual advances. “I have no memory of this incident but I apologise sincerely for anything I ever did that made you feel uncomfortable,” he wrote.

In comments to the media, he said the Vanity Fair article contained a lot of “garbage” but conceded that he had a “very, very rambunctious youth” and that he was “not a church boy”.

Earlier this month, Mr Kennedy was filmed talking to actress Roseanne Barr, recounting the 2014 incident with the dead bear cub.

He said a woman had killed the bear with her car when he was driving in a rural area, and he put it in his van with the initial intention of harvesting its meat.

But ultimately he thought it would be “amusing” to leave the carcass in New York’s Central Park, to make it appear that an errant cyclist had killed the animal. The bear was found the following day.

Responding to a BBC request for comment, New York’s Department of Environmental Conservation said charges could not be brought for incidents more than a year old.