An NYPD officer with Donegal roots prompted the department’s interest in the murder of six-year-old Mary Boyle.
The US cops believe they know who killed Boyle according to a report in the Irish Sun newspaper.
The report says Mary was just six years old when she went missing in 1977.
American officers have visited Cashelard outside Ballyshannon in Co Donegal where Mary was last seen and informally interviewed a number of people.
The paper says they became interested in the unsolved killing after an officer with Donegal roots studied the case for many years.
Singer Margo O’Donnell, a cousin of the missing, girl, told the papers that US officers believe they have identified the person they believe killed the young girl.
She said: “The NYPD are very positive about the person they believe was responsible for Mary’s disappearance. In fact, they say they are 100 per cent positive they know who did it.
“This could be the last throw of the dice in finding her body.”