A former senator has been sentenced to three years in prison, with the final year suspended, after being convicted of extortion.

Francis (Francie) O'Brien from Latton, Castleblayney pleaded guilty to a charge of demanding €100,000 with menaces from a Department of Agriculture vet, Michael Heelan, in Co Monaghan.

The 70-year-old, who served over 20 years as a Fianna Fáil senator, told Leitrim Circuit Court that he was ashamed of what he had done.

Detective Inspector Fergus Traynor said the defendant went to Mr Heelan and said he had been told that blood samples and other animal testing equipment had been found after being incorrectly disposed of.

O'Brien was aware that there had been a previous incident involving Mr Heelan and told him it could go away on payment of €100,000.

The court heard that O'Brien was acting as a messenger for others who were involved.

Mr Heelan went to the gardaí who investigated the case.

They arrested O'Brien when he brought Mr Heelan to a shed to show him the bags of material they had found.

Judge John O'Hagan said the former senator and county councillor had betrayed the trust of people.

Instead of going to gardaí, he had participated in this abominable crime, the judge said.