Alex Fisher's half brother has been charged with his murder.

Eric McIsaac was due to appear in the Levin District Court this afternoon charged with burglary and possession with a knife in relation to the 10 year old's death in Waitarere last month.

Police have announced the additional murder charge ahead of that appearance.

They're thanking the Horowhenua community for help during the inquiry and say there's still work to do in the ongoing investigation.

Detective Senior Sergeant Neil Forlong says the Operation Waitarere homicide investigation team has made good progress, which includes receiving back results from recent forensic testing.