(CNN) -- The Ronald Reagan Presidential Foundation threatened legal action over the online sale of a vial purportedly containing dried blood from the former president following a 1981 assassination attempt.
"If indeed this story is true, it's a craven act and we will use every legal means to stop its sale or purchase," said a statement from John Heubusch, the foundation's executive director.
Bidding for the vial topped 9,181 pounds (nearly $14,500) as of Tuesday, with two days left in the sale. The item is being offered by PFC Auctions, based on the island of Guernsey, a British dependency.
"Dried blood residue from President Reagan ... can be seen clearly in the vial with a quarter-inch ring of blood residue at the end of the inserted rubber stopper," the listing says.
On March 30, 1981, John Hinckley fired six shots at Reagan as the president left the Washington Hilton after delivering a speech. Reagan was rushed to George Washington University Hospital for emergency surgery.
The vial's seller, in a letter of provenance included in the sale, said it has been in his family's possession since the day of the assassination attempt.
"Back in the '70s and '80s, my mother worked for Bio Science Laboratories in Columbia, Maryland," the letter says. The lab was contracted with George Washington University Hospital to handle blood testing, and did Reagan's blood work and testing.
"The test tube and the lab slip that I have are for his blood work to be tested for lead on 03/30/1981," according to the letter. "The testing was completed and the test tube was sitting on my mother's desk."
The seller says in the listing his mother asked the lab director if she could keep the paperwork and test tube, and was allowed to do so. The seller said his mother and father have both since died.
"We've spoken to GW Hospital and are assured an investigation as to how something like this could possibly happen is underway," Heubusch's statement said.
"Any individual, including a president of the United States, should feel confident that once they enter into the care of a medical system, their privacy and rights are held inviolable."
The hospital declined comment to CNN on Tuesday.
The seller said he had contacted the Reagan National Library and spoke to its director, asking if the library would like to purchase the vial. The director said the library would accept the vial as a donation, the seller said, but the director also wanted to check with legal counsel, the National Archives and the FBI, among others.
"He called back in 25 minutes and said that everything was OK," the seller wrote. "The National Archives was not interested in what I had, nor was the Secret Service, the FBI and other agencies. Since 30 years had passed by, he thought that it was simply something that was of no importance at this time and that I was free to do ... whatever I wanted with it."
The seller said he did not want to return the vial to Reagan's family, "since I had served under Pres. Reagan when he was my Commander in Chief when I was in the Army from '87-'91 and that I was a real fan of Reaganomics and felt that Pres. Reagan himself would rather see me sell it rather than donating it."
A form also being sold with the vial contains Reagan's patient ID number at George Washington Hospital, the seller said. The form and a label on the vial contain the names of doctors at the hospital as well, according to the seller.
Reagan served two terms as president. He died in June 2004 at age 93.
Hinckley was found not guilty by reason of insanity in the shooting, which also wounded then-press secretary James Brady, Secret Service Agent Timothy McCarthy and police officer Thomas Delahanty.
Hinckley has been a patient at St. Elizabeths mental hospital in Washington for three decades. A hearing was held earlier this year on his request that he be allowed longer visits to his elderly mother's home in Virginia. A judge in February said he would rule on the matter later.
CNN's Devon Sayers contributed to this report.