Six-year-old Mary Boyle vanished during a family visit to her grandparents' home in County Donegal. Decades of searches, reviews and appeals have not established what happened to her, and no person has been charged in connection with her disappearance.

Mary Boyle was six years old when she disappeared on March 18, 1977, while visiting her grandparents near Cashelard, outside Ballyshannon in County Donegal. Garda records state that she had travelled there with her parents and siblings.
According to accounts later summarized by Irish reporting, Mary followed a relative across nearby fields toward a neighbour's home and then turned back before reaching it. She was not seen again. The family searched locally before Gardaí were alerted, and extensive searches followed.
No confirmed trace of Mary, her clothing or personal belongings has been recovered. The original investigation was followed by later Garda reviews and additional searches using forensic and geology specialists.
An Garda Síochána said a Northern Region review team began another examination in 2011. In October 2014, Gardaí arrested a 64-year-old man on suspicion of kidnapping after investigators said new evidence had emerged. He was questioned and released; no charge followed. The arrest is therefore not evidence of guilt.
The disappearance has generated many public accusations and competing theories. Some individuals discussed in media coverage were investigated and not charged; at least one widely discussed convicted offender was later ruled out after Garda inquiries concluded he was not in Donegal at the relevant time.
Mary's relatives have also publicly expressed differing views about what may have happened. Those beliefs are part of the case's public history, but they are not treated here as proven facts. The evidential record still does not establish who, if anyone, caused Mary's disappearance.
In a renewed appeal issued on the 41st anniversary of the disappearance in March 2018, An Garda Síochána stated that the investigation remained live and ongoing and asked anyone with tangible evidence to come forward.
Mary also remains listed in the Garda missing-person database. That official classification is important: despite the passage of time and repeated suspicion of foul play, there has been no criminal conviction establishing her fate.
Mary vanishes near her grandparents' home at Cashelard, County Donegal.
Large searches and witness inquiries fail to locate Mary.
A Northern Region review team begins a further examination of the case.
A 64-year-old man is arrested on suspicion of kidnapping and later released without charge.
Gardaí state that the investigation remains live and ongoing.
Mary Boyle remains missing. No one has been convicted of causing her disappearance, and the available official record does not establish whether she died accidentally, was abducted, was killed or met another fate. Any future conclusion should depend on new evidence, not speculation.