A chief constable had an affair with his assistant chief constable, resulting in her husband, who was also a police officer, attacking him at home, a tribunal has heard.
Mike Craik, who has since retired from Northumbria Police, was alleged to have been in a relationship with Carolyn Peacock, a fellow high-ranking officer at the force at the time.
Giving evidence at a tribunal, the former head of legal services from the force alleged that Mrs Peacock's chief superintendent husband Jim punched Mr Craik at a barbecue after learning of the affair.
The tribunal in North Shields was convened after Denise Aubrey, 54, who worked in legal services at Northumbria Police for 20 years, was sacked for gross misconduct after she allegedly disclosed information about the affair.
She denies this, and has instead accused her former bosses of "unfair dismissal following a protected disclosure, sex discrimination, disability discrimination, victimisation and harassment".
The names of those involved can now be reported after restrictions at the tribunal were lifted.
The tribunal also heard allegations that an incident log about the altercation was deleted and officers were told not to look for it.
Mr Craik and the Peacocks, who are all retired, were not present at the hearing, but it was said they deny the affair and that the incident at the BBQ ever took place.
In her statement, Ms Aubrey said: "The rumours about Mrs Peacock , a senior Northumbria Police officer, and Craik, a very senior officer, started circulating in 2007.
"I first heard them from a female officer in another force when I was attending a function in Wakefield. Mrs Peacock was mentioned and it was suggested there was 'something going on' between her and Craik."
She said: "One of the stories circulating was that Craik had been having a BBQ at his house when Mrs Peacock's husband, who was also on the force, turned up and punched him.
"It was said that the police were called and Craik was alleged to have insisted that the incident log was removed from the force computer system.
"I have since found out from a former inspector who was the operational commander on duty that the log was indeed removed."
Northumbria Police had sought to stop the allegations being fully reported through requesting the court ban the naming of the three former officers.
But Judge Humphrey Forrester withdrew the order he had initially made after listening to representations on behalf of the press from barrister Gervase de Wilde.
Mr de Wilde said there was significant public interest in the details being known and summarised the force's position by saying "we succeeded in preventing any light being shed on it then so no light should be shone on it now".
Ms Aubrey is accused of revealing details of the affair to her staff at a meeting in June 2013, after which she was suspended and eventually dismissed a year later.
In her case against the force, Ms Aubrey claimed that "overt sexism was rife" and that "a male chief inspector told me that I had been appointed as the token woman".
She alleges that she was bullied by Chief Constable Steve Ashman, who was Deputy Chief Constable when the allegations begin, and that "after two decades of dedicated service,Northumbria Police ruined my life, my mental health and my career".
The hearing was told by Daphne Romney QC, representing Ms Aubrey, the incident that took place in 2007 had attracted attention from Operation Elveden, an investigation into allegations of inappropriate payments to police officers and other public officials.
Ms Aubrey said Northumbria Police had been instructed to investigate whether there had been a leak about the alleged affair, but reported back that as there was no incident log there had been no incident.
She said: "So it is not simply a matter of whether two or three people were involved in a scuffle but also an investigation of how that was used in covering up and misleading a criminal investigation."
Former chief constable Sue Sim is due to give evidence during the tribunal in favour of Ms Aubrey, after sharing a very close working relationship while still at the force.
The case continues.