The former head of the Irish police force ordered that a whistleblower be "buried" over malpractice claims, the alleged victim has said.
Sgt Maurice McCabe was left feeling "isolated" and "alone" after a smear campaign allegedly ordered by ex-Garda commissioner Martin Callinan. The handling of the long-running affair almost brought down the Irish Government last year.
Sgt McCabe faced unfounded and false allegations of sexual assault on a child and a Facebook post described him as "Maurice the Rat" after he made claims of wrongdoing among officers including the quashing of penalty points.
Mr Callinan has denied sending texts to be disseminated among other officers, journalists and politicians raising the fact he had been investigated for sexual assault.
Sgt McCabe told the Disclosures Tribunal in Dublin Mr Callinan's messages to a press officer included: "Do him down, use your phone and do him down. He has to be buried."
Sgt McCabe added: "He would send it on to other senior gardai, ex-commissioner (Noirin) O'Sullivan, and he would send it on to journalists and he sent it on to a number of TD's (parliamentarians)."
The whistleblower also complained of alleged harassment, bullying, discrimination and victimisation at the hands of a superintendent.
He said: "There are an element that would just blank you, not speak to you.
"The culture is there, it is extremely hard to speak out."
He added: "You certainly are isolated and alone."
The senior officer in the Garda, former Commissioner Noirin O'Sullivan, was determined to ensure a safe working environment and dignity at work, letters before the public inquiry into how police handled the whistleblower claims said.
The saga surrounding the treatment of his disclosure of alleged wrongdoing among police in the Irish border counties of Cavan-Monaghan contributed to the end of the careers of former Taoiseach Enda Kenny, two former chiefs of the Garda force and ex-justice minister and later deputy Prime Minister Frances Fitzgerald.
His case was raised with successive Garda commissioners and justice ministers.
Before Christmas, Mrs Fitzgerald resigned to avoid a snap election over her handling of the affair.
The Disclosures Tribunal headed by Judge Peter Charleton at Dublin Castle received oral evidence from Sgt McCabe about his harrowing ordeal on Monday.
That included dealing with rumours about children.
The officer struggled to keep composure as he recalled being told details of claims by the former chairman of a parliamentary Public Accounts Committee (PAC), John McGuinness, which investigated the matter.
Sgt McCabe said: "He said that I sexually abused children."
He was asked to meet Mr McGuinness at a roundabout on the outskirts of Dublin, adding: "He grabbed my arm getting out of the car and said it was very, very serious."
Sgt McCabe said he could not believe what he was hearing and afterwards drove home in a daze.
The witness acknowledged 10 officers he worked with in Mullingar traffic corps had supported him 100% and he had received 300-400 letters, cards and emails of support and no hate mail.
Other documents before the Tribunal also showed that under former Garda commissioner Noirin O'Sullivan, dignity at work seminars were held demonstrating her determination to ensure a safe working environment.
Unprecedented attention had been paid to the McCabe case, the letter from senior management said.
The judge said: "They are taking your position very seriously."
He added structures were put in place to address issues Sgt McCabe had outlined, the feeling he had not been listened to.