Ian Bailey is suing the Irish state after being arrested twice over the killing of Sophie Toscan du Plantier.
The 39-year-old producer was found by two neighbours beaten to death on a hillside outside her holiday home in a remote part of west Cork in 1996.
Mr Bailey denies any involvement in her death and was never charged.
The High Court in Dublin - where the 57-year-old is suing the Irish state for wrongful arrest - heard he thought he had been identified as a suspect when he saw two officers watching him in a newsagents in the days after the killing.
Under cross-examination, Mr Bailey claimed he had been made a murder suspect on "false grounds" and he disagreed with reasons why a person may be detained by police.
Mr Bailey, who is originally from Manchester, said a suspect should only be arrested if evidence "has not been concocted or manufactured".
At one point the former reporter was forced to defend his assertion that he was a correspondent rather than a freelance reporter or "stringer" while he was based in Cheltenham in the 1980s.
When asked why he only provided a small selection of cuttings of his work, Mr Bailey said: "I'm not making it up."
Later Mr Bailey added: "I've come to this court to prosecute Garda [Irish police] corruption and I've brought these as a sample."
Some of the articles discussed related to British intelligence organisation GCHQ in Cheltenham, another involved the print workers' protests at Wapping in 1987, local stories with a royal link and one about a giant pike being caught.
The jury was told Mr Bailey left England in 1991 to get away from the "rat race".
He first went to Arklow, then a farm in Waterford and then a fish factory in Schull, west Cork, and after several long periods on the dole and work on local community projects he attempted to resurrect his journalism career in rural west Cork.
Mr Bailey denied he was in tens of thousands of pounds of debt after his divorce from his first wife was finalised in 1988.
He is to continue being cross-examined in a civil action that is expected to last another five weeks.
The jury of eight men and four women has been told the state denies all claims.
Mr Bailey was arrested on suspicion of the murder of Ms Toscan du Plantier on 10 February, 1997 and again on 20 January 20 1998.
A former journalist who claims he was framed for the unsolved murder of a French film-maker in Ireland has said he should not have been made a suspect.