Suzanne Pilley murder trial: Detectives had no body, no weapon and few clues to work with
They also had to deal with a devious, arrogant suspect, confident he would never pay the price for his crime.
But Gilroy had left a trail of clues. And Suzanne had marked him as her killer – by leaving telltale scratches on his hands and face as she fought for her life.
The first task for police was to establish they were dealing with a murder, not a missing persons case.
So they traced Suzanne’s last movements, and found a normal life stopped in its tracks.
On her last day of life, May 4, 2010, Suzanne made her usual bus trip from her flat in Edinburgh’s Whitson Road to her job at Infrastructure Managers Ltd in Thistle Street.
CCTV showed her getting off the bus on Princes Street and walking towards work.
She was also seen buying food for the day at a nearby Sainsbury’s.
The last CCTV sighting of Suzanne was outside her building, but she never got to her desk.
Gilroy had lured her into the basement car park and murdered her, most likely by strangling her with his bare hands.
Police checked Suzanne’s flat after her parents reported her missing and found her passport, some cash and medication.
Nothing was out of place. Her bank accounts and credit cards were untouched. She had not asked anyone to feed her cat, Mercury, or her tropical fish.
It was clear to police that Suzanne had not simply decided to disappear, nor had she taken her life. She had been murdered.
After killing Suzanne in the car park, Gilroy hid her body in a recess under a staircase and made an excuse to go home for his car.
Colleagues said he was “agitated”, and “shaking”. He was sweating and his eyes were glazed and they saw scratches on his skin.
Gilroy went out on his lunch break and bought air freshener from Superdrug.
Then, before going home to wife Andrea and their two children, he dragged Suzanne’s corpse into the boot of his silver Vauxhall Vectra.
The body lay in the car all night, while Gilroy coolly went to a show at one of the children’s schools and enjoyed a family meal at Vittoria’s Italian restaurant on Leith Walk.
Next day, after driving back to IML’s offices, Gilroy set off for Lochgilphead in Argyll with Suzanne’s body still in the boot.
He told workmates he needed to inspect some pitches at a school the company managed. They were surprised, since the site had been inspected three days before.
At the school, Gilroy asked for black bin bags. He told his boss he had used them for “rubbish from his car which he discarded on the way back to Edinburgh”.
In fact, police believe, Gilroy used the bags to cover Suzanne’s body before burying it in a shallow grave deep in the Argyll forest.
While he was in Lochgilphead, Gilroy got an unexpected call on his mobile – from the police.
Suzanne’s workmates had learned from her office emails of her affair with Gilroy, and the news made him a person of interest to detectives.
Gilroy got the call late in the afternoon and promised to come in as quickly as he could, but it was 11.25pm when he finally showed up at Corstorphine police station.
He was interviewed for 11 hours, as a witness. He freely admitted his affair with Suzanne, and lying to Andrea about it, but said the relationship was over.
Sergeant Paul Grainger, who conducted the interview, said Gilroy seemed happy to talk.
But Paul also noticed a scratch on Gilroy’s forehead and another mark on his neck. Gilroy was asked to come back next day to be examined and photographed.
When he returned, police photographer Louise Harrower saw what looked like make-up on his hands. He had used it to try to cover a number of cuts and scratches.
A detective took Gilroy to the toilet to wash the make-up off but he seemed reluctant. He was “hardly touching” his hands.
The incident was the turning point in how police viewed Gilroy. He had turned himself from a witness into a suspect.
Officers found curved scratches on his hands, a cut on his forehead, scratches to his wrists and forearms and bruising to his chest.
Gilroy said he had hurt himself while gardening but checks at his home did not back that up.
Suzanne was a fit, active 38-year-old woman who had been due to take part in a relay run at the Edinburgh marathon. She would have fought hard for her life.
Pathologist Dr Nat Cary told the trial that victims of stranglers often leave marks on their killers’ bodies. He said some of the marks on Gilroy could have been caused by someone’s fingernails.
Police found no trace of Suzanne in the IML basement. But when they brought in a “cadaver dog” called Buster, trained to sniff out traces of bodies, he showed interest in two areas in the parking bays and one around a door.
Buster also showed interest in two areas of Gilroy’s car boot, and officers noticed a strong smell of cleaning fluid or air freshener.
Detectives staged three reconstructions of Gilroy’s long, winding journey from Edinburgh to Lochgilphead, via Doune, Tyndrum and Inveraray, and back.
They had worked out, from hundreds of hours of CCTV footage, that his outward journey took him five hours and eight minutes. It took the police only three hours.
The police also took three hours to drive back to the capital. Gilroy took five hours and 29 minutes.
It took Gilroy two hours on the return journey to get from Inveraray to Tyndrum. It should only have taken him 40 minutes.
Detectives worked out, by analysing fuel consumption, that 124 miles of Gilroy’s journey were unaccounted for.
And the state of the Vectra – three of four suspension springs were broken and plant matter was stuck to the bottom of the car – suggested he had made a detour off-road.
There were thousands of lonely, wooded spots in Argyll where Gilroy could have buried Suzanne.
But police used tracking signals from his mobile phone to narrow the search to five square miles in the Glen Croe area, near the Rest and Be Thankful beauty spot.
Specialists and volunteers spent several days on an intensive search, backed by RAF Tornado jets with equipment that could spot a scrap of clothing from thousands of feet.
Nothing was found. Suzanne remained in what prosecutor Alex Prentice called her "lonely grave".
But police and Crown lawyers, were still convinced they could put the evidence jigsaw together and convince a jury of Gilroy’s guilt.
At the High Court in Edinburgh yesterday, they were proved right.