An audio expert was paid £2k - at an hourly rate of £100 - by cash-strapped council chiefs to determine whether a councillor swore during a meeting.
Coun Bob Brierley was reprimanded earlier this year for the offhand remark directed at Labour member Coun Stephen Murphy.
Having denied using the offensive term, the controversial independent member faced a code of conduct hearing.
Town hall legal officers employed expert Iain McArthur - who has worked on high profile murder cases - as a prosecution witness at a cost to the taxpayer of £2,160.
Figures obtained by the Evening Post reveal Mr McArthur received the amount for 20 hours work - 16 for “video, work and enhancement” analysis plus four for attending the hearing in person - at an hourly rate of £108.
The standards hearing was overseen by former monitoring officer Linda Fisher who left the town hall in 2016. But council bosses have defended the decision to pay for the top notch expert’s evidence.
Brendan Whitworth, assistant director for legal, said: “To determine if Coun Brierley swore, he having denied doing so, and thus to allow proper consideration of whether there was a breach of the code of conduct we decided to consult an audio expert. There was a cost attached to this but to ensure transparency and fairness we felt it important to have an independent opinion.”
The meeting in question was filmed by council officers with Coun Brierley’s exchange with the Labour member captured on camera. But the often outspoken Hindley Green representative denied using an offensive term and said he would use audio evidence to prove his case and refused to apologise.
Reacting to the remark at the November 2014 meeting, Coun Anita Thorpe said the alleged offensive term “was about his head and another part of his anatomy”.
Ms Fisher had tasked Mr McArthur to assess the footage with his report concluding Coun Brierley did say “Oh, I forgot it’s you Mr Murphy, you ********”.
Asked by Ms Fisher if he thought there was a chance Coun Brierley had said “Oh, I forgot it’s you Mr Murphy, you again” - as he had claimed - Mr McArthur replied: “Absolutely not, 100 per cent.”
Mr McArthur told the hearing he has previously worked on the Milly Dowler and Rhys Jones murder investigations.
The town hall said at the time of the hearing the probe had cost the taxpayer £9,000.