A man in his 20s has been charged with criminal damage over the writing of the word "rat" under the name of Detective Garda Colm Horkan in a book of condolence.
It had been left at the public counter at Blanchardstown Garda Station for the public to sign.
Jason Hennessy (23), from Sheephill Avenue in Blanchardstown, was also charged with violent conduct at Blanchardstown Garda Station while in custody for the criminal damage offence.
He appeared before Judge Gerard Jones at Blanchardstown District Court yesterday morning.
Det Gda Horkan died following a shooting in Castlerea, Co Roscommon, last Wednesday.
A 43-year-old man, Stephen Silver, from Aughaward, Foxford, Co Mayo, has been charged with his murder.
Sergeant Alan Lynch told Judge Jones that on Friday, June 19, he had put out a book of condolence to be signed for their garda colleague Det Gda Horkan.
At 12.15pm he was made aware that two men were at the book and it had been tampered with.
When the book was examined it was seen that the word "rat" had been written under Det Gda Horkan's name and the station stamp had been used to stamp the front of the book.
He said that when CCTV was reviewed Mr Hennessy could be seen to be at the book using the stamp, and while it could not be seen what he had written, he could be observed taking a photograph of it with his mobile phone.
Sgt Lynch said Mr Hennessy's phone has been seized for examination.
He also told Judge Jones that the book of condolence was the property of An Garda Siochana and was due to be presented to the family of the late Det Garda Horkan.
He added that the term "rat" was a very offensive and dangerous thing to write.
No plea was entered and Mr Hennessy's solicitor Simon Fleming applied for bail.
This was objected to by Sgt Lynch, and Judge Jones refused to grant bail.
Addressing the court, Judge Jones said he had been told there was a book of condolence put out for the public to sign and that two males could be seen to be laughing and sniggering at it and that the word "rat" was under Det Gda Horkan's name.
"I'm appalled at the behaviour," he said, adding that it was an allegation at this stage.
"Under no circumstances am I entertaining bail for one minute.
"It's most serious for you and your deceased colleague," he told Sgt Lynch.
He said gardai go out to protect the public and if members of the public deal with them in this manner the courts will deal with them.
"I'm not saying he [Mr Hennessy] is guilty but the evidence is strong," said Judge Jones before refusing bail.
Mr Hennessy was remanded in custody to appear before Cloverhill District Court today, when a date is expected to be set for a High Court bail application.