Det.-Sgt. Savas Kyriacou was leaving home on Boxing Day 2005 for a get-together when the duty desk called just before 6 p.m., propelling him into the investigation ­behind the murder of Jane Creba.

Now that a jury has retired to consider its verdict in the second-degree murder trial of Louis Raphael Woodcock and Tyshaun Barnett, the inside story of the police investigation, dubbed Project Green Apple can be told.

Before he got to the scene, Kyriacou learned that police had already arrested two young males, Andre Thompson, 22, and Jorrell Simpson-Rowe, 17 — the latter carrying a 9-mm semi-automatic handgun — at the Castle Frank subway station some 40 minutes after the 5:15 p.m. shooting.

The next day, Simpson-Rowe admitted to being at the scene but denied firing the gun. He said Woodcock — a.k.a. Big Guy — passed the 9-mm Ruger semi-automatic to him after the shootout.

On Dec. 28, Kyriacou learned that a 16-year-old youth injured at the shooting, who can only be identified as J.J., told officers he had been there by himself and started running when he heard shots. Investigators suspected he was lying.

Dorian Wallace, an English resident illegally in Canada, would, while recovering at St. Michael’s, also claim he had been near the shooting scene by himself.

Similarly Milan Mijatovic, shot in the leg, insisted he was shopping alone at the Foot Locker.

By Dec. 29, police had identified more persons of interest, many of whom were linked.

Forensic tests showed that several cartridge cases found at the scene had been fired by the Ruger handgun carried by Simpson-Rowe.

Woodcock’s DNA was indeed on the gun, but Simpson-Rowe’s was not. Forensics also showed that the handgun did not fire the bullet that killed Creba. It came from a more powerful firearm, possibly a .357-calibre handgun.

Simpson-Rowe said that his group of young males, seven black and one white, had been at the Eaton Centre, then went to the Foot Locker, where they were shot at by a “Vaughan guy” — someone believed to be from the Vaughan Road area — and that Woodcock and his friends shot back.

On March 10, a newspaper reported that police were close to making arrests. The article was wrong, but it yielded an unexpected boon. That day, Vincent Davis got a panicked call from a male, warning him arrests were imminent and that Davis’s friends better “respect the G-Code,” street slang for keeping quiet.

In an unrelated case, police questioned a 24-year-old drug dealer called Jeremiah Valentine about an assault he had witnessed. Valentine gave officers his phone number.

Kyriacou reviewed the March 10 phone call in which someone warned Davis to respect the “G-Code.” The mystery caller’s number matched one of Valentine’s.

Valentine denied any role in Creba’s death but drug dealer Shurlon Trotman gave police a full statement implicating Valentine. He was motivated, he said, by guilt because Creba’s shooting was a violation of the street code that left innocents out of criminal disputes.

Trotman told police that shortly after the Boxing Day gun battle, his friends Milan Mijatovic and Valentine had told him they were together at the Foot Locker and that Valentine fired at an opposing group with his .357-calibre revolver because they felt threatened.

Valentine pleaded guilty to second-degree murder last December and was sentenced to life.