KITCHENER -- The Special Investigations Unit investigated four allegations of sexual assault against the Waterloo Regional Police Service last year, its 2019 annual report shows.

Released on Thursday, the report breaks down the number of cases the province's police watchdog investigated by region.

The unit also investigated two deaths in police custody.

In total, the SIU investigated 11 cases against the WRPS last year:

  • Four custody injuries;
  • Two custody deaths;
  • One vehicle injury; and
  • Four sexual assault allegations.

As an organization, the SIU investigated its lowest number of cases since 2015 with 314 last year. Thirteen resulted in charges being laid.

That's compared to 312 cases in 2015, 327 in 2016, 380 in 2017 and 382 in 2018.

Injuries in police custody were far the most common type of investigation, which made up 55 per cent of cases last year.

The next highest number was sexual assault complaints, which consisted of 18 per cent of the total.

At least five of the SIU's 2019 investigations into the WRPS ended without charges.

Those include:

In each of these cases, the SIU found that there were no grounds to lay charges against the involved police officers.