The Independent Investigation Office of B.C. has concluded its investigation into the 2015 death of Myles Gray, and it's now up to Crown to determine whether charges will be filed against any Vancouver police officers.

On Wednesday morning, the police watchdog confirmed it's ready to file a report with prosecutors on how Gray's life was ended on Aug. 13, 2015.

"In approving charges, B.C. Prosecution Service must be satisfied there is a substantial likelihood of conviction based on the evidence gathered by the IIO and that the prosecution is in the public interest," the IIO said in a press release.

Unlike police agencies, the IIO does not recommend charges to Crown. However, chief civilian director Ron MacDonald must file a report to the Criminal Justice Branch if he believes an officer may have committed an offence.

In an interview Tuesday, Gray's mother Margie told CBC she was relieved the investigation has finally wrapped up, describing the process as "three years, five months and two days of hell."

"It's been a very terrible, traumatizing experience re-living Myles' injuries," she said. "It's kind of nice that this part is over and that it's being moved to Crown … and [I'm] hoping at the end of the day there's going to be charges laid."

Her son, a 33-year-old businessman from Sechelt, B.C., was unarmed on the day Vancouver police were called to an address on Southeast Marine Drive to investigate reports that a man was spraying a woman with a garden hose.

Gray died after a violent struggle in the backyard of a home on Joffre Avenue in Burnaby, B.C. The only witnesses were police officers, and there was no surveillance video of what happened.

An autopsy showed that Gray sustained a long list of injuries, including multiple broken bones, during the struggle. However, B.C.'s coroner was unable to determine an exact cause of death, and had to call in experts from outside the province to assist with the investigation.

According to the IIO, those forensic difficulties are one reason the investigation has taken 41 months to conclude.

Another is a months-long standoff over the responsibility of witness officers to cooperate with investigators. The IIO resorted to filing a petition in B.C. Supreme Court, asking for an order compelling one VPD officer to sit for a second interview.

That petition was withdrawn after Const. Hardeep Sahota agreed to be questioned.