Four preserved foetuses were among human remains found when the FBI raided the warehouse of a man accused of running a fraudulent body parts business.

The discovery was made at the property in Detroit used by Arthur Rathburn, a trader in bodies used for medical research.

Rathburn is due to stand trial in January, having pleaded not guilty to sending customers diseased body parts.

The foetuses, which according Reuters appeared to be between three and six months into a pregnancy, were discovered in a liquid in which brain tissue was also stored.

It is not clear how Rathburn acquired the bodies of the unborn babies or what he intended to do with them, the news agency said.

Rathburn's lawyers have not commented, despite being approached.

Photographs seen by Reuters show foetuses marked with evidence labels.

Members of the House of Representatives called for the matter to be investigated.

Bob Goodlatte, chairman of the House Judiciary Committee, said anyone found to be breaking federal laws and trafficking body parts of unborn children for monetary gain, should be held accountable.

Another Representative, Marsha Blackburn, who recently chaired a special US House committee on the use of foetal tissue, said the discoveries in Rathburn's warehouse raised questions about the practices of body brokers across America.

So-called body brokers take cadavers donated to science, dismember them and sell them for parts, typically for use in medical research and education.

The multimillion-dollar industry relies largely on the poor, who donate their corpses in return for a free cremation of the body parts that are left over after the corpse is dismembered and partly sold off.

Trading in bodies and body parts with the exception of organs used in transplants is legal and largely unregulated in America.

Buying and selling foetal tissue, however, violates US law.

FBI photos that reveal what agents found when they raided Rathburn's warehouse in 2013 paint a grim picture of the unregulated trade.

In all, more than 1,000 body parts were seized, the Detroit Free Press reported.

Details of the case have been gradually emerging in the time since the raid took place.

Among the images seen by Reuters are those that show rotting human heads, some floating face up in a plastic cool box.

Federal prosecutors say Arthur Rathburn and his wife, Elizabeth, ran a black market business dealing diseased human body parts for nearly seven years.

Elizabeth Rathburn, 56, of the Detroit suburb of Grosse Point Park, admitted selling human remains she claimed were disease-free, but which had tested positive for HIV and Hepatitis B, last March. She has agreed to testify against her husband, the Free Press says.

Arthur Rathburn faces charges of wire fraud, aiding and abetting and making false statements. If convicted, he could face up to 20 years in prison.

Source: SkyNews