Hamilton police have arrested one suspect in the Saturday shooting death of Yosif Al-Hasnawi, and are searching for a second man they say is armed and dangerous.

Yosif Al-Hasnawi, 19, was shot and killed near a mosque in Hamilton's central lower city on Saturday evening.

Police have arrested and charged James Anthony Robert Matheson, 20, with being an accessory after the fact to murder. Homicide detectives found him at a downtown home at 3:30 a.m. ET Monday.

Police also released an image of the second suspect — Dale Burningsky King, 19, of Hamilton — who is wanted for second-degree murder.

King is described as a white male with a medium to darker complexion, black hair and a medium build. His hair was long, in a ponytail wrapped at the top of his head at the time of the incident. He was wearing a hood, backpack and jeans.

Anyone who sees King should call 911 and not approach him, police said.

Police are urging him to turn himself in.

"I'm confident he's aware of his status," said Det. Sgt. Steve Bereziuk at a Monday afternoon news conference outside police headquarters.

Yosif Al-Hasnawi, 19, was shot and killed in Hamilton on Saturday evening. (Al-Mostafa Islamic Centre)

'I can't breathe'

Al-Hasnawi, a Brock University medical sciences student, was shot just after 9 p.m. Saturday, while on a break from a religious celebration at the Al-Mostafa Islamic Centre on Main Street East.

Outside with his younger brother, he noticed two people "accosting" an older man, police said. Al-Hasnawi called out for them to stop, attracting their attention.

The suspects crossed Main Street "where they then had an interaction," with Al-Hasnawi and "then took off," east toward Sanford Street.

Al-Hasnawi was shot near Main and Sanford, Bereziuk said.

Police are also looking for the older man too.

Witnesses have been critical of the paramedics.

Paramedics seemed to believe Al-Hasnawi had been shot with a pellet gun, some witnesses said.

'I'm confident he's aware of his status,' Det. Sgt. Steve Bereziuk said of King at a Monday news conference. (Samantha Craggs/CBC)

Amin Al-Tahir, a director at the Al-Mostafa Islamic Centre, said he saw paramedics telling Al-Hasnawi he was fine, and that he was acting.

Al-Hasnawi was on the sidewalk as paramedics examined him, Al-Tahir said. He was talking and moving, but he had difficulty breathing.

"He told them 'I can't breathe,'" Al-Tahir said.

Paramedics said in a statement Monday that they have initiated an investigation.

"[Hamilton Paramedic Service] will ensure that our process is thorough and that all facts are obtained and examined in regards to the event this past weekend," said Deputy Chief Russell Crocker.

"Hamilton Paramedic Service sends its deepest condolences to the family of Yosif Al-Hasnawi during this difficult time."

It is unclear why Al-Hasnawi was taken to St. Joseph's hospital, rather than the trauma centre at Hamilton General, which is closer to the scene.

Al-Hasnawi was shot near the intersection of Main Street and Sanford Avenue. (Andrew Collins)

Just being a Good Samaritan

Bereziuk described Al-Hasnawi as an athlete who boxed, ran and played basketball. His family immigrated to Canada from Iraq in 2008.

"He stepped in in an attempt to calm the situation down, to neutralize it, to do the right thing," Bereziuk said.

"He was being that Good Samaritan."

Al-Tahir said the Muslim community is grieving the loss. It will hold a ceremony in Canada before returning Al-Hasnawi's remains to Iraq this week.

Police ask anyone with information or who witnessed the Saturday incident to contact Det. Doug Jonovich at 905-546-4863.