The Irishwoman hastily arrested on suspicion of causing the death of Rehma Sabir was an unlikely candidate for a child killer.
Louise Woodward, who was convicted of involuntary manslaughter in Massachusetts in 1997, was a young, inexperienced teenager who'd been working as a nanny less than a year when an eight- month-old died in her care.
Aisling Brady McCarthy was a mature, married woman in her mid thirties, and had been a nanny for more than a decade when she was arrested for the murder of the one-year-old girl she was looking after, also in Massachusetts, in January 2013. She didn't fit any of the usual profiles, but from the start police and prosecutors were convinced Rehma had died from so-called Shaken Baby Syndrome (SBS), and that Brady was to blame, despite the presence of unhealed bone fractures in the baby pre dating the Irishwoman's period of employment, among other inconsistencies.
Last week, after more than two years in jail and five months under house arrest, Brady McCarthy, now 37, was finally freed after the District Attorney dropped the homicide charge. This followed the medical examiner's decision to change the cause of death in this tragic case to "undetermined", on the grounds that "enough evidence has been presented to raise the possibility that the bleeding could have been related to an accidental injury in a child with a bleeding risk or possibly could have even been a result of an undefined natural disease".
Bad decisions are made in haste, but it takes years to put them right. Rehma's death was ruled by doctors to be caused by SBS within 24 hours, and Brady was charged before an autopsy had even been conducted on the dead child. The focus now is on why and how she fell victim to this miscarriage of justice.
It's certainly true that being an immigrant, especially one who arrived in the country in 2003 on a visa waiver programme that only allowed her to stay for three months, must have made her situation more difficult; but this case had nothing to do either with Aisling Brady McCarthy's nationality or undocumented status.
Rather, it's the latest instalment of a saga which has been playing out in the States for some years now over convictions secured on the basis of a diagnosis of SBS. Thousands of Americans may be wrongly in jail as a result, many on death row. Figures suggest the conviction rate of those charged with SBS is 95pc, with more than 90pc receiving life sentences.
The scientific orthodoxy states that a baby must have been violently shaken if it exhibits three symptoms - subdural bleeding (blood collecting between the brain and the skull), retinal bleeding (bleeding in the back of the eye), and brain swelling.
Law professor Deborah Turkheimer, who wrote a book on the subject called Flawed Convictions, describes how this triad has become in effect "a medical diagnosis for murder". In any case where these three factors were present, conviction was inevitable; but doubts arose about the accuracy of these diagnoses as long ago as 1987, when it was discovered that small accidental drops or falls could produce exactly the same injuries. Even so, defendants are being repeatedly convicted on this basis alone, without any other evidence or witnesses.
Odd as it may seem, Aisling McCarthy Brady was lucky. Drayton Witt, an Arizona father, served 10 years in jail before his own conviction was overturned when the medical examiner recanted his evidence in similar circumstances. In his case, the child was subsequently found to have died as a result of a stroke caused by an underlying medical condition.
Shirley Smith, a California grandmother, also spent 10 years behind bars before being granted clemency when a child in her care died during the night. Most infamously, there is Jennifer Del Prete, a day care worker from Chicago who checked on a 14-month- old baby called Isabella that she was minding, found her to be unresponsive, and was then arrested for doing harm to the child, who subsequently died 10 months later in hospital.
She too served 10 years in jail, separated from her own children, before a review of the case by US District Court Judge Matthew Kennelly last year led to her release.
Kennelly not only found that De Prete's conviction was "highly suspect", but also concluded that the medical evidence which was being used to secure these convictions had become "more an article of faith than a proposition of science". His dismissal of the evidence against her was an important development.
In most instances, those wrongly accused have either had their convictions downgraded to lesser offences or else have seen charges against them dropped because of lack of evidence. Del Prete's review, by contrast, ruled that she had done enough to establish "actual innocence".
This is the nightmare facing Aisling. Of course it's a relief that she has been set free and allowed to return to Ireland; but she still hasn't been officially declared innocent. Local news reports in the US went very much with the line that prosecutors were letting her go because they "simply don't have enough information to carry on with this murder charge".
That is not the same as having one's good name restored, but while police and doctors in the States remain stubbornly unwilling to concede that they were wrong about this incident from the start, she remains technically free but with a cloud of suspicion hanging over her in the eyes of many. Even in Del Prete's case, prosecutors remain bullish that her original conviction was correct. If those in Massachusetts also dig in their heels, Aisling faces the same uphill battle to fully clear her name, one which could be every bit as ruinously expensive as that to free her in the first place. Justice is not cheap.
Her dogged defence lawyer, Melinda Thompson, always maintained that the cause of baby Rehma's death was unclear, and that there were other factors which should have been taken into consideration, and last week she branded her client's treatment at the hands of the US authorities a "complete disgrace", because the crime for which she was arrested had never actually happened.
But that's not what police and prosecutors are saying yet, and there's little evidence they will behave towards her in future with anything other than petty vindictiveness.
Thompson laughed cynically when expressing a hope that her client would be allowed a few days respite before heading home to Ireland with dignity. True to form, Brady McCarthy was immediately made surrender to immigration authorities and deported as a "significant violator", meaning she will face a 10-year ban before she is allowed to return to the States. Not that she will be rushing to do so, considering her ordeal, but it was a mean-spirited gesture.
She may have breached immigration rules, but they wrongly branded her a child killer. They should apologise, not add insult to injury.
She's not the only one who has been subjected to trial by innuendo either. Knowing Aisling was innocent of wrongdoing, many of her supporters were quick to point the finger of suspicion at other members of baby Rehma's family who also had access to the child in the hours running up to her death. If this really was nothing more than a natural tragedy, then those people have had mud flung at them unfairly too, and at the worst possible time in their lives.
There are lots of victims in this case, and the fact that most of them aren't Irish shouldn't make us any less indignant on their behalf too.