An excavation has begun in Tuam, County Galway, at the site of a former church-run institution where investigators believe the remains of nearly 800 children may be buried in an unmarked mass grave.

The effort follows years of public outcry, survivor testimony, and independent research into the burial practices at the St Mary’s mother-and-baby home, which operated between 1925 and 1961.

The site was once home to St Mary’s, a state-supported and church-managed institution where thousands of unmarried women and their children were housed.

The institution was operated by the Bon Secours Sisters and became a focal point of scrutiny after local historian Catherine Corless uncovered death records for 796 children who died while in care at the facility.

Her findings, published in 2014, were based on the absence of corresponding burial records and suggested that the children may have been interred in what had once been a disused sewage tank.

On Monday, machinery moved onto a green plot adjacent to a children’s playground in a Tuam housing estate, marking the start of a two-year operation.

Daniel MacSweeney, director of the excavation, described the process as unprecedented due to the age and condition of the remains.

Infant bones, he noted, are extremely fragile, with some femurs measuring no longer than an adult’s finger.

The goal is to recover remains with maximum care to enable identification.

The death records span from 1925, when Patrick Derrane died aged five months, to 1960, when Mary Carty died at the same age.

Corless’s initial investigation was sparked by anecdotal evidence from a cemetery caretaker and historical inconsistencies in burial records.

Old maps showed the site in question had been labelled as a sewage tank in 1929.

A later map from the 1970s included a handwritten note identifying the area as a burial ground.

Testimony from residents further supported these findings.

Mary Moriarty, who lived near the site in the 1970s, recounted seeing what she described as tightly packed bundles in a chamber beneath the ground, wrapped in decayed cloth and arranged in rows.

Her account was supported by others in the community who had heard similar reports of bone discoveries by children.

In 2017, a government-commissioned test excavation confirmed the presence of significant quantities of juvenile human remains at the site, with estimated ages at death ranging from approximately 35 weeks gestation to three years old.

The site had operated as a workhouse during the Great Famine before being converted into a mother-and-baby home.

Survivors of the institution and their families have long campaigned for a full excavation and proper recognition of the children who died there.

Anna Corrigan, a campaigner whose mother gave birth to two sons at the home, only discovered their existence later in life.

One of her brothers, John, has a death certificate listing "congenital idiot" and "measles" as causes of death.

There is no burial location recorded for either John or his brother William.

Survivors from the home recall long-lasting social stigma and systemic exclusion.

PJ Haverty, who spent his early childhood at St Mary’s, described being segregated at school and referred to as a "home child." Many of those who lived at the home have expressed a desire for formal acknowledgment of the children who died.

The Tuam excavation is part of broader efforts to address the legacy of Ireland’s mother-and-baby homes.

Similar investigations are underway or planned at other former institutions across the country.