Warning: This story contains graphic details.

FBI agents found buckets of body parts and a man's body with a woman's head sewn onto it, among other gruesome discoveries, during a 2014 raid of a body-donation center in Phoenix, Arizona.

The Biological Resource Center, which has since been closed, had been selling the body parts for profit, for as much as $2,900, according to documents in a civil lawsuit reported this month by the Arizona Republic and KTVK.

The facility received bodies from family members by offering free pickup and cremation, the Arizona Republic said.

Relatives are suing the center, with some saying they donated bodies thinking that they were contributing to scientific research.

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FBI agents found buckets of human body parts and a torso with the head from another body sewn onto it in a horrific 2014 raid at a for-profit body-donation center in Phoenix, Arizona, recently published court documents say.

The agents made the gruesome discoveries at the Biological Resource Center in January 2014, but details of the raid were recently revealed via an eyewitness testimony in a civil lawsuit filed against the center, the Arizona Republic and KTVK reported this month.

Mark Cwynar, the FBI special agent who gave the testimony, recalled seeing "various unsettling scenes" during the raid, according to the Arizona Republic. He also described some of his discoveries as a "morbid joke," KTVK said.

Here's what he saw, according to the Arizona Republic and KTVK's reporting from court documents:

A "bucket of heads, arms, and legs."

A "cooler filled with male genitalia."

A woman's head sewn onto a larger male torso, like "Frankenstein," hanging on a wall.

"Infected heads." It's not entirely clear what this means.

Bodies that had been cut up with chainsaws and bandsaws. The bodies didn't have ID tags.

"Pools of human blood and other bodily fluids" on the freezer floor.

Why the facility stored the body parts and treated them as such is not clear.

Old footage taken outside the Biological Research Center, which has since been closed. KPHO-TV via Arizona's Family

The FBI raided the center after it was accused of selling the donated body parts for a profit, ABC 15 Arizona reported.

Citing the court documents, the Arizona Republic said the most expensive item the facility sold, a "whole body with no shoulders or head" was $2,900, while a foot was $450. It wasn't clear who the body parts were sold to.

The Biological Resource Center was closed in 2014 after the raid, but lawsuits from families who donated bodies are ongoing.

Thirty-three plaintiffs are suing the center, with some saying they thought they were donating their loved ones' remains for scientific research or organ donation and that the bodies were not treated with dignity or respect, the Arizona Republic reported.

Their case is set to go to trial on October 21, the newspaper added.

FBI agents raided the Biological Resource Center in 2014. CBS 15 via Arizona Attorney General/YouTube

The facility accepted bodies from families in exchange for free pickup and, later, the cremated remains of body parts it did not sell, according to the Arizona Republic.

Troy Harp, a plaintiff who donated the bodies of his mother and grandmother to the center in 2012 and 2013, told KTVK that he received what he was told were his mother's ashes shortly after the 2014 FBI raid but that he wasn't sure they were really hers.

Stephen Gore, the Biological Resource Center's owner, pleaded guilty in 2015 to operating an illegal enterprise and was sentenced to one year deferred prison time and four years probation.

According to the Arizona Republic, Gore wrote in a letter to a judge in 2015 that he "could have been more open about the process of donation on the brochure we put in public view."

"When deciding which donors could be eligible to donate, I should have hired a medical director rather than relying on medical knowledge from books or the internet," he added.

Court filings say he is representing himself in the latest civil suit, the Arizona Republic reported, adding that it had not been able to contact Gore.