A Toronto police officer has been charged with second-degree murder in connection with the September 2010 shooting death of a Toronto man, Ontario's Special Investigations Unit said Thursday

Const. David Cavanagh has been charged after an investigation into the shooting of Eric Osawe, 26, who was killed while police tried to execute a search warrant at an apartment on Dunbloor Road, near Kipling Avenue and Bloor Street.

Cavanagh was originally charged with manslaughter in late 2010, but the agency upgraded the charge following their investigation.

A family friend described Osawe at the time as a troubled young man who had recently been released from prison.

His 23-year-old brother Ebony was also in the apartment. Police arrested Ebony and charged him with five firearms-related offences.

A preliminary inquiry is scheduled for Oct. 1.

It is the first time a Toronto police officer has been charged with murder stemming from an on-the-job incident.

Toronto Police Association president Mike McCormack said the murder charge sends a "disturbing message" to police officers.

"To suggest that an officer performing his duties executing a search warrant with a team would have intent to murder somebody is absolutely appalling," he told reporters. "We've lost confidence in the Crown attorney's office and the SIU for our members to be treated fairly and impartially."

McCormack questioned why the charges were upgraded, saying there was no new evidence since the initial investigation.

He also spoke of worries from officers about what the charge could mean for their jobs.

"We have to know that when we're making split-second decisions and taking action ... that our actions will be judged fairly and this clearly indicates to my members that they won't be," McCormack said.

Toronto police said it could not comment on the charges, as it is an SIU investigation.

The SIU investigates reports involving police where there has been death, serious injury or allegations of sexual assault.

Cavanagh is free on bail and has been suspended with pay.