Australia news live: three dead and man arrested in Sydney; Liberals claim seat of Nepean in key Victorian byelection

A third victim has died and a man is in police custody following an incident at a home in Sydney’s southwest, AAP reports.NSW police arrived at the house in Rosemeadow on Sunday at 1.30am after reports of a disturbance.Officers found a 64-year-old man suffering serious head injuries, along with the bodies of a woman in her 60s and a man in his 20s.The injured man received medical treatment from NSW ambulance paramedics and Liverpool hospital, but later died.The bodies are yet to be formally identified.Police say the victims “were assaulted by a man known to them”.Police arrested a 32-year-old man, who was taken to Campbelltown police station for questioning.Officers have set up a crime scene and are preparing a report for the coroner.The Liberal party has claimed victory in a key Victorian byelection seen as a preview of what to expect when the rest of the state hits the polls in November.As counting continued in the Mornington peninsula seat of Nepean, the Liberal candidate, Anthony Marsh, appeared to be in a commanding position in a significant boost to opposition leader Jess Wilson.With close to 80% of the vote counted, Marsh had 38.5% of the primary vote, and 63.4% on a two-candidate basis.Read more from AAP here:A third victim has died and a man is in police custody following an incident at a home in Sydney’s southwest, AAP reports.NSW police arrived at the house in Rosemeadow on Sunday at 1.30am after reports of a disturbance.Officers found a 64-year-old man suffering serious head injuries, along with the bodies of a woman in her 60s and a man in his 20s.The injured man received medical treatment from NSW ambulance paramedics and Liverpool hospital, but later died.The bodies are yet to be formally identified.Police say the victims “were assaulted by a man known to them”.Police arrested a 32-year-old man, who was taken to Campbelltown police station for questioning.Officers have set up a crime scene and are preparing a report for the coroner.And welcome to another Sunday Guardian live blog.This morning, Nationals leader Matt Canavan will be appearing as a guest on ABC Insiders.In Victoria, state opposition leader Jess Wilson claimed victory for the Liberal party in a key byelection in the seat of Nepean, ahead of a state election in November.This morning in Sydney, there will be a paddle-out across the harbour in support of the Global Sumud Flotilla, which included six Australians, and was intercepted by Israeli defence forces while attempting to deliver aid to Gaza.And Japanese prime minister Sanae Takaichi is expected to arrive in Australia tonight, in her first official visit since taking office. She will meet with prime minister Anthony Albanese in Canberra tomorrow for the Australia–Japan Annual Leaders’ Meeting.I’m Petra Stock and I’ll be taking the blog through the day.