Jones, 85, is standing trial in Sydney after pleading not guilty to 22 counts of indecent assault and sexual touching without consent against six men between 2003 and 2020.
One complainant is a former radio staffer who claimed he was repeatedly non-consensually kissed and groped by the longtime breakfast shock jock over five months.
He confided years later in Hadley, who was Jones's rival and stablemate at leading Sydney radio station 2GB.
Hadley returned to the witness box on Wednesday, when Jones's barrister Gabrielle Bashir SC referred to explosive text messages between Hadley and the man.
One exchange occurred after the staffer's allegations were first aired in a 2023 article by Sydney Morning Herald journalist Kate McClymont.
"The low c**** will now know he is not just taking on victims, he's taking on me and Kate," Hadley texted the alleged victim.
"I won't rest until we bury him, figuratively and literally."
In another expletive laden text, the rugby league commentator said: "That c*** will be in the foetal position when he reads the story in the morning. It's been 50 years in the making."
He promised "one by one I will tear his supporters apart" in another missive that named a famous cricketer.
After being taken to a broadcast where he called a 2GB broadcaster "a denier" on air, Hadley accepted he was prepared to denigrate those whose accounts differed from the radio staffer's.
But he denied trying to silence anyone or force them to change their stories and rejected a suggestion he had a vested interest in the outcome of Jones's case.
Hadley denied he was prepared to tailor his evidence to damage his rival or support the prosecution case.
He accepted he had not provided copies of his text messages to the court but appeared resigned and unsurprised as they were read out.
The texts, produced by the complainant, included Hadley referring to Jones being "outed as a f*****" around the time the staffer confided in him.
When asked if he used the homophobic slur to refer to Jones, the former 2GB mornings host said it appeared to be the case and used it in that instance but maintained it was not a word he normally used.
Pressed on whether he harboured animosity towards Jones at the time of the staffer's report, Hadley replied he "wasn't happy with him".
Hadley said he had previously been informed of an assault allegation brought by a co-worker which went nowhere because CCTV footage cleared him.
He testified he had been told by a "double agent" colleague Jones had been involved in the allegation.
"(He) assured me Jones had marshalled the troops and said, 'dig up some dirt on Hadley'," Hadley said.
He agreed he told police he later stormed into the former Wallabies coach's office and called him a "dog and a c***", which he characterised as "advice" about his rival's work.
Hadley had previously signed a "secret contract" worth $4 million to take over as breakfast show host but it was ultimately torn up when the chairman of Nine - which owns 2GB - insisted Jones return, he said.
"Inadvertently, Mr Jones had doubled my salary for doing the same job," Hadley told the court jovially, insisting he wasn't bitter.
Ms Bashir suggested Hadley wanted to destroy his rival and encouraged the radio staffer to make a complaint to that end, which the radio giant denied.
During his own evidence, the radio staffer rejected suggestions he fabricated the indecent assault claims or came forward to benefit Hadley.
Jones denied all of the charges, which are alleged to have occurred during the latter part of his 35-year broadcasting career, when he dominated Sydney's airwaves and won the breakfast slot a record 226 times.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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