Australia's monarchists have issued their support for King Charles amid an ongoing police investigation into his brother, Andrew Mountbatten-Windsor - but have questioned Prime Minister Anthony Albanese over his letter supporting the former prince's removal from the line of succession.Andrew Mountbatten-Windsor was arrested on his 66th birthday last week and held for 12 hours before being released without charge.UK police said the arrest was part of an investigation into suspected misconduct in public officer.READ MORE: Two arrested over alleged kidnapping,