Mark Ludbrook, 53, admitted he killed his friend Autumn Baker at his Hoppers Crossing home in Melbourne's southwest on August 3, 2023.
But he denied he was guilty of murder, claiming his mind was altered by the illicit drug PCE and he had no control of his actions.
The Victorian Supreme Court jury was told Ludbrook took the drug on the morning of August 3 to manage chronic pain from his diagnosed transverse myelitis.
His carer Amber Davison described his strange behaviour before the alleged murder, where he was seen walking around naked despite normally only managing three steps at a time.
Ludbrook also thanked different colours and told his carer how he needed to sleep with her to save the animals, Ms Davison told the jury.
Ludbrook's barrister Emily Clark said her client's behaviour showed he was in an altered state of mind so he could not have consciously, deliberately or voluntarily carried out the killing.
Crown prosecutor Jim Shaw argued while Ludbrook was clearly drug-affected, he was still conscious of his actions and should be found guilty of murder.
The jury was sent out to deliberate on August 25 but was unable to reach a unanimous verdict.
Justice John Champion discharged the 12 jurors on Thursday afternoon.
Ludbrook will face a fresh directions hearing in the Supreme Court on September 16.
9°C