Sergeant Brett Hanley first approached the small house shortly after midnight, noticing both the lights and television were on inside, he told the court.
He explained seeing a woman lying on her back not far from the door and entered the lounge.
"To me it was clear the person was deceased," Hanley said.
"I leaned down and felt her wrist for approximately 15 seconds trying to see if there was any pulse.
"At that time, I stepped over the deceased female to have a look at the state of the injuries."
Hanley said he believed there was a blanket wrapped around the woman's neck and he also noted there was a "red-handled hammer lying in a pool of blood".
"It was an injury that I believed was totally incompatible with life," he said.
"I noticed there was a lot of blood that went all the way up the wall as well. At that point I went out of the scene the way I came in."
Hanley made the decision to close down the scene and radioed to confirm an ambulance was en route.
A paramedic later arrived and confirmed the woman had died.
Today, the victim's brother, Mate Marinovich, was also called to give evidence in the trial.
He lived on the same property as his sister but in a separate house and told the court on the night of February 7, she had been in good spirits.
He also told the court what he remembered of his nephew.
"He had a completely expressionless face and never said a word to me.
"It was most unusual. That's all I can say."
Earlier today, Crown prosecutor Elena Mok alleged Martin Marinovich became so angry he snapped, tried to strangle his mother and struck her at least 12 times with a hammer.
She said it likely followed an argument between the two in the cramped and dirty Oratia home they shared.
He had been caring for her after she was discharged from hospital, the court heard.
"It is plain the defendant was isolated and under a great deal of strain in the lead-up to that night," Mok said.
The argument was the final straw, she said.
They might never know "what specifically prompted" the argument.
However, the Crown said there could not be doubt: "He is responsible for her murder."
But Defence lawyer Shane Tait said the central issues the jury needed to focus on during the trial was the idea of murderous intent and whether or not the defendant had suffered from mental illness.
The trial continues tomorrow.