Detective Constable Rebecca Bryant kept it secret that juror Lauren Jones was her son’s girlfriend, and sent texts telling her “Don’t tell them who you are” on the eve of the murder trial in 2016.
The officer’s relationship to Miss Jones was only discovered after Dwayne Edgar, Jake Whelan and Robert Lainsbury were sentenced to life in prison for knifing 29-year-old Lynford Brewster to death in Cardiff.
Their convictions were quashed by the Court of Appeal as a result, only for all three to again be jailed for life after a re-trial earlier this year.
Jonathan Rees QC, representing DC Bryant, argued that the disgraced officer should be allowed to keep her job with South Wales Police as her actions did not amount to gross misconduct.
The hearing in Cardiff was told a psychologist who assessed DC Bryant was “90% certain” she was suffering from post traumatic stress disorder during the original trial, brought on by watching “harrowing” CCTV footage of Mr Brewster’s murder.
Mr Rees said: “The evidence is that it is 90% probable that at the time this officer was suffering from PTSD.
“The psychologist is 99% certain that would have affected her thinking at the time.
“She was working on a particularly harrowing case, viewing CCTV footage of a murder which occurred on camera and which triggered post traumatic symptoms.
“Sleep disturbance, flashbacks, hyper-vigilance, highly anxious.
“Symptoms all of which in her opinion would have affected her clarity of thought. But symptoms that would not necessarily be apparent to others.”
Mr Rees said DC Bryant was “genuinely remorseful” for her actions, and said she was “thankful those responsible for murder have not escaped justice”.
The hearing was read extracts from an interview with DC Bryant after admitting her dishonesty, where she said: “I was embarrassed. I feel like I’ve let everyone down. I just feel terrible.
“I’ve never tried to appropriate blame to anyone other than myself.
“I am acutely aware of the gravity of my mistake. I can promise it will never happen again.
“I fully understand the impact on South Wales Police and the family of Lynford Brewster.”
Mr Rees added: “There is no evidence she intended to undermine the criminal justice process.”
Presenting officer Jeremy Johnson said in response that any PTSD suffered by DC Bryant at the time of the trial “does not begin to explain the quite extraordinary conduct of this officer”.
DC Bryant admits breaching standards of professional behaviour relating to her failing to disclose her relationship to Miss Jones, advising her to mislead the court to attend a hair appointment, and denying she knew Miss Jones when confronted by colleagues.
But she denies that her advising to Miss Jones about her hair appointment was dishonest behaviour, or that her actions amount to gross misconduct.
The hearing continues.