The prosecution case against Irish nanny Aisling Brady McCarthy has suffered a potential setback after evidence from the physician was dismissed in another shaken-baby case.

Reports in the Boston Herald say prosecutors were taken aback when charges against a Malden man accused in a similar case were dropped before he had to stand trial.

Middlesex District Attorney Marian Ryan dropped the prosecution of  Geoffrey Wilson who was accused of killing his 6-month-old son Nathan in 2010.

His attorney had argued that a congenital condition was the reason for Nathan’s death and not shaken-baby syndrome.

The ruling raises serious issues surrounding Dr. Alice Newton, the doctor who diagnosed shaken-baby syndrome in Wilson’s case.

She also handed down the same assessment in Irish nanny Brady McCarthy’s case.

The report says McCarthy’s lawyers are already in the process of trying to discredit Newton.

Newton herself could not be reached for comment by the paper but expert lawyer Elaine Whitfield Sharpe, who represented English nanny Louise Woodward, said the ruling is a blow for the prosecutors in the Boston nanny case.

She said: “It shows that this doctor misdiagnosed a condition in one instance, and that has some relevance when defense attorneys cross-examine her.

“You can’t bring up the finding in the case, but you can ask her about it. You could ask, ‘Is it true, Dr. Newton, that you diagnosed the baby in the case of Nathan Wilson?’ If she responds, you can ask whether she heard about the outcome.”

The report says that such a line of questioning, if permitted by the judge, could quickly pick apart the physician’s credibility.

Sharpe said they can also ask whether she ‘missed the diagnosis’ in Wilson’s case and that could paint her as an unreliable witness in the eyes of jurors.

McCarthy’s lawyers have already worked with Wilson’s attorney J.W. Carney Jr.

He agreed to let McCarthy’s attorneys look over his client’s family history last month because they were ‘very sympathetic when there’s a situation where someone has been wrongfully charged with murder.’

The Boston Herald says the latest decision seems to indicate that Middlesex prosecutors aren’t fully confident in Newton anymore.

The paper says the nolle prosequi could also be a more far-reaching knock against the now-controversial shaken-baby syndrome diagnosis, the target of a small but growing group of physicians.

Dr. Robert Rothfeder, a physician and attorney who has spoken out against shaken-baby syndrome as an expert witness, said: “That case is typical of what’s going on around the country right now.

“In the minds of some, these physical findings are tantamount to DNA evidence, but that’s certainly not the case.”