A garda detective found guilty of harassing a State solicitor by sending her abusive letters and emails has been sentenced to three years in prison.

Eve Doherty, 49, a detective sergeant based in Dublin, was convicted of harassing Elizabeth Howlin, who worked with the DPP, between September 2011 and March 2013.

The court heard she was in a relationship with the victim's former partner.

Judge Melanie Greally said the offence was malicious and insidious, and had a severe impact on the victim.

The trial heard that over an 18-month period letters and emails were sent to Ms Howlin's workplace, to her boss Claire Loftus, to her GP Frank Marmion and to her home.

She was called "corrupt", "useless" and "incompetent", which the solicitor found very upsetting and distressing and an invasion of her privacy.

Obscene and insulting language was used and Ms Howlin was told "we are all watching every move you make".

Doherty's defence counsel Michael O'Higgins described it as "hideous and defamatory".

A4 posters were also left around Ms Howlin's housing estate in Blackrock falsely claiming she was a political appointee who would "pull" files to prevent the prosecution of anyone connected to her or the Government.

Ms Howlin is a distant cousin of the TD Brendan Howlin and their two pictures were put on the posters.

Gardaí put Doherty under surveillance and found her sending an email from a city centre internet café wearing a wig and dark glasses. She also wore a black beanie and scarf over her face.

They then searched her home. When they compared the emails and documents found there and in her work locker, they identified multiple examples of 60 common features, such as grammatical errors.

Two letters found in her locker began "well smart bitch - still going through hell, I hope you are" and "ha ha ha, find a job yet".

Doherty denied the charges, but a jury found her guilty of harassment.

The judge took into consideration her lack of previous convictions, the difficulty for a garda in prison, her academic and employment achievements, and her kindness to neighbours and concern for animals.

She was sentenced to three years in prison.