Steve and Denise Potter have campaigned for five years on behalf of Shane Cribb, a former boyfriend of one of their daughters.
Mr Cribb was convicted on a charge of careless driving causing injury on the false testimony of a police officer, but the conviction was later quashed.
"All we wanted was for the truth to come out," Mr Potter said after the sentencing of former constable Dairne Cassidy. Her conviction on a charge of attempting to pervert the course of justice followed former senior constable Neil Ford's September conviction for perjury.
"This might be seen as the end of the matter, but it's not quite," Mr Potter said.
The couple wrote to the Independent Police Conduct Authority "right from day one" expressing their concerns about the way police had handled the case. There were still some unanswered questions, they said.
"It's a result, but you have to keep in mind what this has done to a lot of people and the toll it's taken," Mr Potter said.
