The fate of Lord Black of Crossharbour, once one of the most powerful press barons in the world, will be decided by a mother of three who is viewed as one of the rising stars of the US judiciary.

The swaggering former chairman of the Telegraph Group is to be sentenced in his US fraud case in Chicago on Monday by Judge Amy St Eve, 42, who stands at just over 5ft. But Black can take no solace from her “distractingly attractive” appearance.

The daughter of a Midwestern dentist made her reputation as a prosecutor investigating the former business partners of Bill Clinton, when he was President, in the Whitewater scandal, and is now regarded as a tough pro-prosecution judge. As a woman picked by the Republican president to become the youngest judge appointed to the federal bench in Chicago at the age of 36, she is tipped to become a US Supreme Court justice.

“She comes across as a young, very perky, non-threatening person as a judge,” Michael Deutsch, a defence lawyer who has appeared before her in a recent terror-related case, said. “But she comes from a strong, government background as a US attorney for many years.”

At the hearing Judge St Eve will determine whether Black, 63, spends the rest of his life in prison, as the prosecution demands, or gets out in as little as five years.

“Prison would be a bore, but quite endurable,” Black, on $21 million (£10 million) bail, said in e-mails to the Canadian Broadcasting Corporation. “I can get on with anyone and adjust to almost anything and I don’t consider it [prison] shaming.”

As a former assistant US attorney in Chicago, Judge St Eve worked with several of the prosecutors who are pushing for Black to be sent away for up to 30 years.

“I think her background as a prosecutor should cause defendants to have a little bit of fear here,” Hugh Totten, of the Chicago law firm of Perkins Coie, who has followed the case, said.

He added that Judge St Eve might find that the prosecution has gone too far in demanding what would effectively be a life term for Black.

Born in the southern Illinois town of Belleville, Judge St Eve studied history, then law at Cornell University. She joined the New York law firm of Davis Polk and Wardwell, specialising in white-collar crime. She became a federal prosecutor in Chicago before being nominated to the bench in 2001 by George Bush.

But that did not stop an internet blog entitled Underneath Their Robes naming her the No 9 “superhottie” on the US federal bench in 2004, quoting lawyers saying that her “distractingly attractive” appearance made it “difficult to appear before her”.

Judge St Eve raised eyebrows this summer by clearing her courtroom to allow Israeli agents to testify in camera in a terror-related case. She then meted out an 11-year prison term to a Palestinian who refused to give evidence to a grand jury.

Mr Deutsch, a lawyer in the case, called the sentence “unprecedented” and “obscene”.

During jury selection for Black’s trial, one potential juror noted that she had read in the local newspaper that Judge St Eve ran a “tight ship”. “Running a tight ship is not a bad thing,” she replied.

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