Terrence Freebody, 89, was found dead on the floor of his neighbour's Red Hill home in July 2012.

He had suffered fatal knife wounds.

The homeowner, Luigi Costa, 71, has pleaded not guilty in the ACT Supreme Court to murder.

The Crown alleges Costa pushed Mr Freebody off a chair, stomped on his face and neck, and then stabbed and cut him with the intention of disposing of his body.

Costa's defence team says their client is not guilty due to mental impairment, arguing he suffers from dementia.

The court has heard the Freebodys lived across from Costa on Mugga Way and had been invited to his home for a drink on the afternoon of July 22.

But Costa's repeated use of foul language saw Mr Freebody's widow leave about 5pm.

Costa called triple zero for assistance only minutes later.

Police arrived about 5.30pm to find Mr Freebody dead and Costa in a nearby toilet, covered in faeces and blood on his hands.

A bloody knife was found on a nearby sink.

The court heard from police crime scene investigators as the trial entered its fifth day on Wednesday.

Jurors were shown pictures of the crime scene and taken on a tour of the home via a digital walk-through system used by police.

Pictures showed Mr Freebody lying dead on the dining room floor.

Faeces and blood could be seen in both the kitchen and dining room.

Police forensics officer Fiona Knott, who analysed evidence collected from Costa in the hours after he was placed under arrest, gave evidence from the witness stand.

Ms Knott said swabs taken from Costa's hands and shoes detected blood that matched Mr Freebody's.

Ms Knott also described different types of blood spatter.

When asked by the defence if the evidence revealed a frenzied attack, she responded that it had been a dynamic crime scene.

Prosecutor Shane Drumgold closed his case on Wednesday.

The defence is expected to begin calling witnesses when the trial continues on Thursday.