Dr Crippen was convicted of killing his wife and hanged in 1910
A distant US relative of Dr Hawley Crippen, executed in London in 1910 for murdering his wife, has failed in a bid to secure a posthumous pardon for him.
The Criminal Cases Review Commission refused to send the case back to the Court of Appeal, saying the applicant was not a "properly interested person".
James Patrick Crippen, 73, of Ohio, a second cousin three times removed, said he was "disappointed" by the decision.
He argues remains found at Crippen's home were not those of his wife, Cora.
He said DNA tests had proved this, casting serious doubt over his ancestor's conviction.
James Crippen has been fighting for years for an appeal, a royal pardon and the release of his relative's remains, which are buried in the grounds of Pentonville Prison, London.
Mr Crippen, who lives in Dayton, told the BBC News website: "It's an embarrassment to the British courts to have to admit, after 100 years, that the gentleman was innocent.
"They didn't want to review the case - it's so old they felt they shouldn't change it. They just leave our name in disrespect."
The former marketing manager said he would be consulting his UK lawyers about the "other avenues".
The Criminal Cases Review Commission (CCRC) decided James Crippen was not a "properly interested person" in the case and there was no real possibility the Court of Appeal would hear it.
The commission said in cases where the person whose conviction is to be appealed against was dead, the request must come from someone "approved" by the Court of Appeal.
Crippen and his mistress Ethel Le Neve went on trial at the Old Bailey
That person should be the widow or widower, "personal representative", or a relative who has a "substantial financial or other interest" in the appeal.
"Without an individual who has a real possibility of being approved by the Court of Appeal, there could be no court hearing and so no purpose would be served by the commission carrying out a review of the case," said a CCRC spokesman.
The commission, which had received the request in May, said it considered the application "impartially and in detail" but concluded last month that James Crippen did not meet the test.
It is understood the CCRC did not examine the grounds for the appeal.
The CCRC spokesman said Mr Crippen's representatives could apply to the Administrative Court for permission to seek a judicial review of the decision.
The appeal was launched after scientists at Michigan State University claimed to have obtained DNA evidence in 2007.
The researchers said they had tracked down three of Mrs Crippen's grandnieces and compared their DNA with samples from the body which had been kept on a microscope slide since the Old Bailey trial.
The Crippen case is one of the most notorious in British criminal history.
After hiding his wife's remains under a cellar, the US-born doctor tried to escape to Canada on the SS Montrose with his lover Ethel Le Neve, who was disguised as a boy.
But he was caught after the ship's captain recognised him from newspaper reports and alerted Scotland Yard.
The Montrose was the first ship to carry Marconi's new telegram system and Crippen famously became the first criminal in history to be arrested thanks to such technology.
He was arrested at sea and brought back to Britain after Inspector Walter Dew made a trans-Atlantic dash in a faster vessel.
Crippen was found guilty and hanged at Pentonville Prison in November 1910.
Le Neve, who was tried separately for complicity in the killing, was acquitted.