GLENDALE, Ariz. (AP) — A federal law enforcement agency confirmed it's opened an investigation into Robert F. Kennedy Jr. after he allegedly cut off the head of a dead whale and took it home two decades ago.

The former independent presidential candidate disclosed the investigation on Saturday while campaigning outside Phoenix for Donald Trump.

Kennedy’s daughter recalled the whale incident in a 2012 interview with Town and Country magazine, which recently resurfaced and was shared extensively on social media. Kathleen Kennedy said when she was 6 years old, her dad got word that a dead whale had washed ashore. He got a chainsaw, cut off the whale’s head and strapped it to the roof of their minivan for a five-hour drive home.

“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,” Kathleen Kennedy recalls. “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.”

A spokesperson for the National Marine Fisheries Service confirmed Monday that authorities investigating but declined to elaborate, citing a policy against commenting on open investigations. The agency, part of the National Oceanic and Atmospheric Administration, enforces federal laws including the Marine Mammal Protection Act and the Endangered Species Act.

Kennedy told a crowd of Trump supporters in Glendale, Arizona, that he received a letter “saying they were investigating me for collecting a whale specimen 20 years ago."

Without confirming or denying he took the severed whale head, Kennedy said the deadline to bring charges passed long ago. He implied without evidence that the investigation was tied to his endorsement of Trump.

Kennedy repeatedly declined to elaborate on the investigation when questioned by reporters after his appearance, saying the media only wants to talk to him about “gossipy nonsense.”

“I’m not interested in feeding that feature of the mainstream media,” Kennedy said.

The whale carcass is the latest bizarre episode involving Kennedy and a dead animal.

Last month, Kennedy said he once retrieved a bear that was killed by a motorist and left it in New York’s Central Park with a bicycle on top, sparking a mystery that consumed the city a decade ago.