In a country that is estimated to have one CCTV camera for every 32 people, it is not suprising that one of Britain's biggest terrorism cases was solved by images caught on tape.
On the morning of July 7, 2005, four bombs detonated in London – three on the city's subway, one on a double-decker bus. Fifty-two people died and more than 700 were injured. The attacks, known as London 7/7, are considered the worst act of home-grown terrorism in Britain.
The four bombers, British Islamists, were killed in the blasts, but were identified later with the help of 6,000 hours of closed-circuit television footage. It shows the bombers on the morning of July 7 before they boarded the subway. The four men are seen arriving at the subway platform; later footage shows one of the bombers travelling on a bus, which later exploded, killing 14.
A riot broke out in downtown Vancouver in 2011 after the Canucks lost Game 7 of the Stanley Cup final to the Boston Bruins. In its investigation, Vancouver police relied on more than 6,000 hours of raw video from a number of sources.
Some of that video was used for a website Vancouver police set up – called Vancouver Riot 2011: Help Identify Suspects – which allowed people to view photos and identify suspects. More than 2,000 Web tips were received; more than 50 investigators worked the case, going through photos and videos to capture faces and identify pieces of clothing.
The painstaking process drew criticism because of the months-long wait for charges to be laid. Many of those charges are still making their way through the courts.
Toronto's G20 protest
Police used video in its probe of the 2010 G20 summit protests, which saw a number of incidents of vandalism downtown, including the setting on fire of four police cars.
Investigators looked at more than 80,000 photos and videos; once a person was identified as being linked to an act of vandalism, they were followed through other videos by way of distinctive features and items of clothing.
Toronto police also have a YouTube channel of surveillance videos posted for public identification purposes.
In this case, however, raw video footage from the arrests after the protests also led to an investigation of the Toronto police force, after a video surfaced of protester Adam Nobody being beaten by police.