A Hamilton officer accused of downplaying the shooting injury of a 19-year-old Good Samaritan has been cleared of wrongdoing in the young man's death, the province's police watchdog said Thursday.

The Special Investigations Unit's report details the confusion surrounding the injuries sustained by Yosif Al-Hasnawi, who died on Dec. 2, 2017 after trying to help a stranger being accosted outside a mosque, and conflicting witness accounts about whether a real gun or a pellet gun was used in the incident.

Al-Hasnawi had stepped in to help an older man who was being harassed by two other men that night. Police allege one of the men shot and killed Al-Hasnawi. He faces charges of second-degree murder while the second man was charged with accessory after the fact.

Two paramedics have also since been charged with failing to provide the necessaries of life after an independent investigation into the incident by neighbouring Niagara Regional police.

The SIU announced last year that it would be investigating the Hamilton police officer in relation to the fatal shooting and has determined that he didn't contribute directly or indirectly to Al-Hasnawi's death.

"He neither delayed, nor interfered with, the medical assessment and treatment of (Al-Hasnawi)," SIU director Tony Loparco wrote in a report on the officer, who isn't named.

Police had received a 911 call at 8:56 p.m. that night from a man at a convenience store who believed he heard a gunshot, the SIU said. Several officers arrived on scene quickly, including the officer who was the subject of the SIU probe.

That officer spoke with Al-Hasnawi, looked at his abdomen with his flashlight and called for an ambulance eight seconds later, the report said.

The officer reported a pellet or "BB gun" was possibly involved and that Al-Hasnawi had "minor injuries, superficial to abdomen," according to a recording of the dispatch.

The report noted that several witnesses said Al-Hasnawi was shot, but many said it was with a pellet gun. One thought it was a real gun and another thought the 19-year-old was injured by what sounded like a firecracker.

Al-Hasnawi was on the ground, complaining about pain in his abdomen, the report said.

Several witnesses also reported seeing the injury and believed it to be minor, the report said. Attending firefighters described the wound as "a little tiny, so small, wound in his lower belly" with "almost no blood."

Witnesses said police officers accused Al-Hasnawi of faking or exaggerating his injury -- some claimed officers were laughing and joking around while Al-Hasnawi writhed in pain on the ground. Other witnesses said the officers acted professionally. The SIU dismissed the claims because they conflicted and could not be linked to a specific officer.

"Nor is there any evidence that the behaviour of any police officer present interfered with, or prevented, the paramedics from assessing the complainant's condition and providing him with the necessary medical care and attention," Loparco wrote.

A forensic pathologist noted a single bullet entered Al-Hasnawi's body and left a "tiny wound, zero point five millimetres ... a very small hole basically ... in the low abdomen," the report noted.

"The pathologist further determined that two major blood vessels, an artery and a vein, had been damaged by the bullet which resulted in a massive bleed with two litres of blood being found to have pooled in the abdominal cavity," the report said.

Another half litre of blood had clotted in the abdominal wall, "which led to the conclusion that the complainant had lost a significant amount of blood volume internally, which was the direct cause of his death."

It's unclear when paramedics arrived, but the report notes Al-Hasnawi arrived at hospital about 40 minutes later, at 9:39 p.m. and went into cardiac arrest a minute later. At 9:58 p.m. doctors stopped trying to resuscitate Al-Hasnawi and pronounced him dead shortly thereafter.

The SIU said its probe was further complicated by the fact that it was not officially notified for nearly five months of the alleged police negligence, although it said it knew about the witness allegations within days through media reports.

"The delay in notification eliminated the possibility of the SIU gathering any evidence independent of the police investigations," Loparco wrote.

A member of the public complained to the Office of the Independent Police Review Director about three weeks after Al-Hasnawi died, but the SIU said the OIPRD didn't notify them of alleged police negligence until April 27, 2018.

A Hamilton police spokesman said the force does not comment on SIU investigation outcomes.