The foundation of former US President Ronald Reagan has expressed outrage after a vial said to have held a sample of his blood was put on sale in an online auction.
UK-based PFC Auctions says the blood was taken from Reagan after the failed 1981 assassination attempt against him.
The PFC website put the latest bid at £7,587 ($12,000) on Tuesday.
John Heubusch, executive director of the foundation, said that, if true, it would fight to stop "this craven act".
"If indeed this story is true, it's a craven act and we will use every legal means to stop its sale or purchase," he said.
He said the hospital where Mr Reagan had been treated had assured the foundation that an inquiry was under way into "how something like this could possibly happen".
PFC Auctions, based on Guernsey in the British Channel Islands, said it had had no contact with the Reagan Foundation.
It displayed a picture of the vial on its website bearing a label showing the president's name.
The site says "dried blood residue" can be clearly seen in the five-inch glass vial.
The lot includes a letter of provenance from the seller who says their late mother worked at the laboratory which carried out blood testing for George Washington University Hospital after Mr Reagan was shot.
"These articles have actually been in my family's possession since... the day that President Reagan was shot in Washington DC," the letter reads.
It continues to explain that the seller contacted the foundation offering to sell it but the foundation was not interested in purchasing it, only receiving the vial as a donation.
"I was a real fan of Reaganomics and felt that Reagan himself would rather see me sell it rather than donating it," the anonymous seller - who says he was in the US army between 1979 and 1991 - writes.
However, the BBC has spoken to a source who, in 1981, was working at Bio-Science Laboratories in Maryland, which is cited by the seller as the facility which conducted the tests.
While confirming that several vials of President Reagan's blood were received for analysis after the attempted assassination, the source is not aware of material having being retained or removed by staff.
Mr Reagan suffered a punctured lung and internal bleeding when he was shot by John Hinckley Jr outside the Washington Hilton Hotel.
Mr Hinckley was later found not guilty by reason of insanity and is being treated at a psychiatric hospital.
Mr Reagan, who went on to serve two terms as president, died at the age of 93 in 2004.