O'Doherty joined the
Irish Independent in 1995 as a staff writer, In 2013,
Roy Greenslade in
The Guardian, at the time she was fired from the
Irish Independent, described her as "one of Ireland's leading investigative journalists", but mentioned concerns over the ethics of her newsgathering methods. In 2018, another Irish journalist,
Michael Clifford, questioned the impact of her investigative work and her use of "theories of conspiracy". In 2010, O'Doherty wrote an article highlighting issues in the investigation into the
1985 death of a priest, Niall Molloy, after a society wedding in
County Offaly that included senior Irish political figures, and the collapse of the subsequent manslaughter trial. Her work led to the reopening of the case. According to O'Doherty, her research had "exposed a cover-up of staggering proportions involving several institutions of the State and the Catholic Church." In 2015, a Garda review of the case concluded that the original Garda investigation was correctly concluded. In April 2013, while investigating the
penalty points cancellation scandal, O'Doherty sought to question Garda Commissioner
Martin Callinan about the quashing of his own speeding points and called to his private home at approximately 10pm in order to do so, speaking to Callinan's wife. In August 2013, Doherty was fired from the
Irish Independent and, though the newspaper rejected any links between the events, editor-in-chief
Stephen Rae branded her as a "rogue reporter" for approaching the commissioner without editorial permission. The Irish
National Union of Journalists condemned the dismissal as unfair. As part of the apology, Independent Newspapers stated that it wished to "acknowledge the exceptional work of multi-award winning investigative journalist Gemma O'Doherty for the Irish Independent during the course of a lengthy career". In 2016, she produced a documentary,
Mary Boyle: The Untold Story, about the disappearance of a child in 1977, which was published on
YouTube. The
disappearance of Mary Boyle is the longest running missing child case in Ireland, and the documentary implies political interference in the investigation. It led to O'Doherty being sued for defamation by
Fianna Fáil politician
Sean McEniff for damages of €75,000. In 2019, after McEniff's death, a judge granted his estate leave to continue the case. In late 2017, O'Doherty wrote an article, published by
Village magazine, concerning allegations of long-term child sexual abuse in
Terenure College,
Dublin, and followed it up in early 2018 with allegations that the Gardaí did not act on information they had about issues regarding the college's rugby coach, John McClean. A year later, McClean was formally charged with indecently assaulting nine students in Terenure College over a 17-year period. In August 2019,
Village published an editorial on O'Doherty and her relationship with the magazine. It described her as "the It girl for Irish extremism: racism, anti-Islamism, homophobia and transphobia". It defended her previous freelance work for the magazine, saying "O'Doherty's politics were not offensive until some time after Village published its last piece by her" and concluded by stating that "Once O'Doherty revealed herself as racist she was no longer welcome in these pages". In August 2021, O'Doherty and
John Waters launched a
freesheet newspaper titled
The Irish Light, largely consisting of anti-vaccine propaganda and other conspiracy theories. It is run in conjunction with
The Light, a UK publication, and reprints much of the UK version's articles. In December 2022, Edel Campbell, the mother of Diego Gilsenan, a minor who had died by suicide, called for the removal of her son's image, and that of 41 other people, from the cover of
The Irish Light. Their images had been used without permission in videos posted online by O'Doherty, and in a cover story of the freesheet, which linked their deaths to the Covid vaccine. The images used included those of people who had died from suicide and Katie Moran, a
camogie player who had died following an incident during a match. ==Politics==