The ABC reports, citing court documents, Donald Day Jr — a convicted felon who posted online under the pseudonym “Geronimo’s Bones”, — agreed to plead guilty to possessing firearms while a felon.

In return, prosecutors will reportedly drop several other charges, including allegations tied to threats against US law enforcement officials.

Day’s case drew attention after investigators found he had been in contact with Gareth and Stacey Train. The couple fatally shot Queensland police officers Matthew Arnold and Rachel McCrow and neighbour Alan Dare during a 2022 ambush at Wieambilla.

Court records say the Trains published an bizarre video on YouTube after the shootings, declaring authorities had “came to kills us and we killed them”.

The pair signed off the video with a message to Day.

“We’ll see you at home, Don. Love you,” they said.

Day replied online that he wished “that I could be with you to do what I do best”.

In another post, he praised his contacts as his “brave brother and sister”, saying they had “done exactly what they were supposed to do, and that is to kill these f***ing devils”, the documents state.

US authorities initially charged Day with a string of offences, including threatening the director-general of the World Health Organisation and police, as well as weapons offences.

His plea agreement in Arizona records the charge he will admit to — possession of guns and ammunition while a felon.

The court papers also catalogue Day’s criminal history.

He received multiple sentences after a 1986 conviction in California for violence against authorities. Other listed felonies include larceny in Wyoming in 1987, a 1990 prison assault in California and possession of stolen property.

Three remaining counts will be dropped under the deal — two alleging threats and one alleging possession of an unregistered firearm. One of the dropped counts concerned an incident during Day’s arrest in December 2023, when he was accused of warning FBI officers: “If anything happens to my wife, and I ever get out of these cuffs, I’ll come for every fng one of you. How’s that? You better kill me, if you f my wife up, you hurt her in any way, you better kill me here and now.”

Day’s email rant

In an email rant to news.com.au, Day claimed Gareth and Stacey Train turned down an invitation from him to relocate them to the US before they carried out the deadly ambush on the Queensland Police officers.

Instead, the man claimed, they stayed in Australia to “weather the storm”.

News.com.au reporters made the link between the Day, who ran a small-time anti-government YouTube channel, and the Trains through a series of videos and a letter.

The December 18, 2023, email defended the Trains’ sinister actions and criticised media “hit pieces” on the trio.

It also revealed that he offered the Trains asylum in the US amid the Covid-19 pandemic.

“I asked the Trains to abandon the hell that Australia has become and relocate to America … they chose to weather the storm of tyranny inundating their homeland and to fight against it,” Don said.

News.com.au turned the email from Day over to the police investigating the incident shortly after receiving it.