Statistics released this week show 2016 was the bloodiest year in Ottawa's recent history, and both police and criminologists are narrowing their focus on three theories to help explain why.

According to the Ottawa Police Service's 2016 annual report, the severity of violent crimes committed in the capital rose sharply in Ottawa last year, matching a trend seen in cities across North America.

2016 saw 24 homicides in Ottawa, up from seven the previous year. Ottawa's homicide rate — the number of homicides per 100,000 people — rose to 2.6, rivalling the rate in Toronto.

So what accounts for this worrying rise? Or is it just a violent blip? There are several theories, but these three are the most prevalent among police and scholars.

1. The Ferguson Effect

One idea swiftly gaining popularity at criminology conferences is what's known as the Ferguson Effect, a reference to the police shooting of Michael Brown in Ferguson, Mo., in 2014.

According to the theory, rising public scrutiny of police treatment of young men from racialized communities actually leads to an increase of crime in some neighbourhoods, because police tend to back away from those areas to avoid the very confrontations that attracted scrutiny in the first place.

Insp. Jamie Dunlop with the Ottawa Police Service thinks the concept may have some merit. He said officers are concerned proactive policing in high-crime areas could lead to complaints from the public, but at the same time don't want criminals to feel "free to move around" in those neighbourhoods.

"That means we have to try to find a new way of doing business if we're trying to balance those two," Dunlop said.

According to the 2016 annual report, complaints against officers leading to disciplinary action shot up by 97 per cent last year.

Officers have to be conscious of the fact that they are being accused of things more often. - Insp. Jamie Dunlop, Ottawa Police Service

"Officers have to be conscious of the fact that they are being accused of things more often," Dunlop said.

The resulting effect is what criminologists call "de-policing," and is the focus of a PhD thesis by former Ottawa police officer Greg Brown.

Brown, who spent 28 years on the force — eight of them investigating homicides — has surveyed more than 3,000 police officers from across Canada and New York state as part of his doctoral research at Carleton University's Department of Sociology.

"It's indisputable that officers are disengaging," he said. "Officers are very concerned about being recorded, as well as the uptick in public criticism, and skepticism."

While some theorists are already making the connection, Brown said any firm link between de-policing and the recent increase in violent crime has yet to be established.

2. The power vacuum

It may sound counterintuitive, but research has suggested successful police operations targeting organized criminal groups can leave power vacuums which can in turn spark turf wars and beget more violence.

According to this theory, police have become the victims of their own success. Or more accurately, people living in high-crime neighbourhoods have.

According to Dunlop, nearly half of the 24 homicides in Ottawa last year involved gang violence. He also noted that a number of key gang figures arrested in 2008 were recently released back into the community, which can also cause problems.

University of Toronto criminologist Scott Wortley said it's hard to make a connection between police crackdowns and a jump in the homicide rate.

3. Limited resources

Despite last year's leap in violent crime, crime rates in Ottawa and elsewhere have enjoyed a general decline over the last decade. That's placed pressure on police forces to trim their budgets.

But with fewer officers on the ground and increasing reliance on "virtual" policing through projects like Ottawa's new Strategic Operation Centre, the stage is set for violence to erupt.

When that happens, Dunlop said, "our response is certainly stretched.... If we have multiple violent offences on one given night, then the available officers to respond to the calls for services are severely strained."

It's nearly impossible to explain what's going on based on a single year's data, Wortley warned.

Of course, there could be a variety of factors at play. Even the weather could have had a role: 2016 was the hottest year on record, Wortley noted, and warm weather tends to bring more crime.

And six months into 2017, the pace of violent crime in both Ottawa and Toronto is slowing, with homicide rates trending back toward pre-2016 levels.