A United States man known only as Don has been arrested concerning a religiously-motivated terrorist attack in Australia, during which two police officers and another man were murdered. Police allege the man, known only as “Don” in videos, was in contact with members of the Train family before their murdered police officers Matthew Arnold and Rachel McCrow and neighbour Alan Dare during the horrific shooting at Wieambilla in December last year. Constables Arnold and McCrow were killed by Nathaniel, Stacey and Gareth Train on December 12, 2022, when they went to the remote Western Downs bush block to investigate a missing person’s report concerning Nathaniel. Alan Dare, their neighbour, was also shot and killed by the trio. The Trains were followers of an extremist Christian ideology known as “premillennialism” — the belief Jesus Christ would return to earth after a period of extreme suffering. In the hours following the shooting, Stacey and Gareth uploaded a chilling video to YouTube where they admitted to killing the officers and Mr Dare, communicating with a person known only as “Don”. In a statement on Wednesday, Queensland Police confirmed a 58-year-old United States national had been arrested in Arizona in connection with the shooting. On Wednesday, QPS Assistant Commissioner Cheryl Scanlon said the police investigation linked the US national and his exchanges with Gareth and Stacey over YouTube years beforehand. Commissioner Scanlon confirmed Wednesday that the arrested US man was the “Don” discussed in the Trains’ video. “On November 29 at Tucson, Arizona, two indictments were issued by a grand jury for interstate threats under the US S 875c,” Commissioner Scanlon said. “One of those threats relates to comments posted online in December 2022, inciting violence in connection with the incident at Wieambilla.” She said the 58-year-old man was arrested in Heber Overgaard, Arizona on December 1. The man appeared in a US court and was remanded in custody. Commissioner Scanlon said the investigation was ongoing, and a search warrant had been executed at a remote property 30km north of Heber Overgaard in northern Arizona. She said one of the man’s indictments related to “online activity” concerning the Wieambilla matter. Commissioner Scanlon said the motivation of the US man was still under investigation. She said it was known Gareth Train began following the man on YouTube around May 2020. The pair began commenting directly on each other’s videos in May 2021. “We have evidence to show the Trains subsequently accessed an older YouTube account created by the same man in 2014 and viewed that content,” Commissioner Scanlon said. “Between May 2021 and December 2022, the man repeatedly sent messages containing Christian end-of-day ideology to Gareth and then later to Stacey,” she said. “Evidence has been seized and is being analysed by the FBI.” The man is not currently known to QPS investigators, Commissioner Scanlon confirmed. She said part of the investigation also involved probing who else had been in contact with the man. Investigators from the QPS Ethical Standards Command and the Security and Counter Terrorism Command travelled to the United States of America to pursue the investigation. “On Friday morning, December 1, 2023 (US time), FBI Agents arrested a 58-year-old United States national near Heber Overgaard, Arizona, in connection to the religiously-motivated terrorist attack on December 12, 2022, at Wieambilla,” Queensland Police said in a statement earlier on Wednesday. “Investigations by the QPS and FBI are ongoing in Arizona. “The state coroner and families of Constables Matthew Arnold, Rachel McCrow, and neighbour Alan Dare, along with other officers involved, have been briefed on the progress of this investigation.” Members of the Train family — brothers Nathaniel and Gareth Train and his wife Stacey — murdered both constables when they attended the Wains Rd property near Tara. The officers were conducting a welfare check on Nathaniel, a former NSW school principal reported missing months earlier. A third constable, Keely Brough, fled into bushland when the trio fired upon her while a fourth officer, Randall Kirk, was injured. Mr Dare was killed by the trio when he came to investigate smoke coming from the property, caused by fires the Trains had lit to flush out constable Brough. Nathaniel, Gareth and Stacey were all killed during a shootout with police later that night.