"I believe this T-shirt had been strategically placed on the side of the chest of drawers so it could be seen when entering the bedroom," Detective Sergeant Tara Phillips wrote in her statement.
It was Edwards' twisted final act in the cold-blooded murders of his two children Jack and Jennifer, calculated to inflict unbearable pain on his ex-wife Olga after a bitter split.
On Monday, a coronial inquest began into the horrific murder-suicide that shocked Australia two years ago.
Olga wrote in a family court affidavit in 2016 of her "tremendous fear" she would one day come home to find her 15-year-old son dead at the hands of his father.
The full extent of 67-year-old Edwards' evil plan was laid bare for the first time this week.
After the custody battle, he wasn't meant to know where his kids were living.
At his post-mortem a bloodstained piece of paper with 13-year-old Jennifer's train timetable and movements printed on it was found in his pocket.
Police have never figured out how he got it and suspect he may have hired a private investigator.
But Edwards burned his tablet and mobile phone before he died, cutting off possible leads.
In the days before the murders, he hired a nondescript rental car his children wouldn't recognise.
He also picked up two guns from St Marys Pistol Club. He was in a flustered mood, slamming the door to his pistol locker so hard it jammed and had to be fixed with a screwdriver.
On the afternoon of July 5, he lay in wait for more than an hour at Pennant Hills railway station before spotting Jennifer.
His rental car was captured on CCTV tailing her bus, and then her eight-minute walk from the stop to her West Pennant Hills home.
At 4.59pm, as Jennifer was entering the house, Edwards pulled up. Inside, he fired 14 rounds into his kids with a Glock semiautomatic. Their bodies were found crumpled under Jack's desk. By 5.01pm he was gone.
Olga, who emigrated from Russia to marry Edwards when she was 19, was left in an unfathomable world of pain.
She remained in the Hull Rd home because "it still had some of Jack and Jenny in it".
She showed photos from the morgue to her doctor, trying desperately to reconstruct her children's last moments based on their bullet wounds.
She took her own life in December 2018, aged 37.
An inquest into the tragedy this week revealed Olga was the last of seven women, and Jennifer and Jack the youngest of 10 children, who had the misfortune of calling John Edwards family at one point or another.
After Olga reported Edwards had assaulted Jack and Jennifer, she was asked to bring the kids to the station.
When she didn't, her complaint was labelled "no offence detected" and closed without further investigation, the inquest heard.
The officer noted down the report as a possible "premeditated attempt" by Olga to influence family court proceedings.
This all ran against NSW Police domestic violence standard procedures, which the officer who dealt with Olga read for the first time as she gave evidence.
Six weeks later, in a scene straight from a horror film, Olga opened her eyes after lying down in a 6am "hot yoga" class to see Edwards standing behind her, reflected in the mirrors lining the studio walls.
She went back to Hornsby police station and met with a different officer, who told the inquest this week he thought her complaint was a "tit-for-tat" about who got to go to which yoga class.
Counsel assisting the coroner Christopher Mitchell asked him: "Wasn't it relevant John was staring at Olga?"
"Yep but I don't know if you've ever been to a yoga class," the constable replied. "They all face in one direction."
Whether anything would have been different if police had responded appropriately to Olga's reports is one of several questions Coroner O'Sullivan is seeking to answer.
How on earth Edwards was granted a gun licence is another. Firearms registry staff are among the 40-odd witnesses slated to be called.
Both the firearms registry and NSW Police say they have made changes to their systems since Jack and Jennifer died.
Also under scrutiny is the Family Court, where Olga and Edwards were locked in an acrimonious battle from April 2016 to February 2018.
A children's lawyer appointed to advocate for Jack and Jennifer insisted the kids told her they still wanted to see their dad before a hearing in December 2016.
This was "surprising", counsel assisting the coroner Kate Richardson SC replied, as Jack and Jennifer told everyone else involved in the case they feared him.
An interim order that the kids see Edwards every Saturday for three hours was never adhered to, the teenagers old enough to vote with their feet.
Olga won full custody on Valentine's Day in 2018.
Her death is not formally being investigated at the inquest, but her efforts to protect her children from Edwards have consumed much of the evidence.
Her boss remembered her as a bright and impressive solicitor, and her yoga instructor as someone with a "happy, light, joyous" personality.
Jack was a cheeky and endearing little boy who struggled — no wonder — with school and his behaviour in his teenage years.
A former teacher sobbed on the witness stand, so distraught her voice cracked even as she took the oath, as she remembered Jennifer.
The "kind and gentle" girl was going to channel her intellect and love of animals into becoming a veterinarian.
But Jennifer, whose middle name was Angel, would never get any older than 13.
Around 5pm on July 5, 2018, Bruce Wilson was watching the sunset on his back veranda, as he does every day, when an "almighty bang" pierced the tranquillity.
He put down his cup of tea and walked next door, hearing more bangs as he went.
There, he saw a man walk out of Olga's house and calmly proceed down the stairs, not using the handrail.
Wilson knew something horrific had just transpired. He eyeballed the stranger, determined to commit to memory his hair colour, build and the contours of his face.
"What have you done?" he asked, as the man walked straight towards him. He didn't get an answer.
The man moved methodically to his car and backed out of the drive so slowly that Wilson, continuing to scrutinise him through the window, kept pace.
It was perhaps the last interaction John Edwards had with another human being before he arrived home, erected his pathetic T-shirt tribute to himself, and ended his own life.
Wilson watched the car disappear into the distance. Then he retraced Edwards' steps, up to the wide-open door of the house, and stopped.