Hamilton police say a criminal investigation has been launched into the on-scene medical care first responders provided Yosif Al-Hasnawi, a Good Samaritan who was fatally shot after intervening in a dispute.

Al-Hasnawi, 19, was shot Dec. 2 after coming to the aid of an older man being verbally accosted by two men on Main Street East in Hamilton's lower city. It happened just outside the mosque where Al-Hasnawi had attended an evening religious celebration.

Witnesses at the scene were critical of Hamilton paramedics, saying they told Al-Hasnawi that he was acting, and that he'd been shot by a pellet gun.

Police later confirmed 38 minutes passed from the time paramedics arrived until the ambulance took Al-Hasnawi to hospital, where he died shortly after.

Hamilton police issued a media release Wednesday saying Niagara Regional Police will handle the case "to ensure a fair and impartial investigation is completed."

The investigation was handed over after "a review of the preliminary evidence," said Const. Jerome Stewart. Police aren't sure how long it will take.

The city and the Ontario Health Ministry are also investigating.

In a statement earlier this month, deputy chief Russell Crocker said the paramedic service is "committed to a high standard of care for all of its residents."

Al-Hasnawi was buried this week in his native Iraq. Two Hamilton men are charged in connection with his death.

Dale Burningsky King, 19, is charged with second-degree murder. James Matheson, 20, is charged with being an accessory after the fact to murder.