London (CNN) -- Controversy continues to surround the death of 29-year-old Mark Duggan in north London on Thursday evening.
His shooting at the hands of police while he was travelling in a taxi cab sparked rioting and looting in Tottenham on Saturday. The unrest subsequently spread across London and other parts of the UK in what police have described as copycat attacks.
How did Duggan die?
Officers from Operation Trident -- the Metropolitan Police unit that deals with gun crime in London's black communities -- stopped the cab Duggan was travelling in during a pre-planned operation.
Duggan, a father of four, died of a single gunshot wound to the chest, an inquest at north London Coroner's Court heard on Tuesday. The inquiry was told that the incident occurred at 6.15pm local time and that Duggan was pronounced dead at 6.45pm.
There are varying accounts of the sequence of events -- initial reports from the IPCC said that during an apparent exchange of gun fire police officers fired two shots and Duggan died at the scene.
There was a suggestion that officers could have come under fire from the car carrying Duggan.
This assumption came from the fact that a bullet had lodged in a police radio worn by an officer at the scene, raising speculation he might have been fired at from the vehicle.
A non-police issue handgun was also recovered at the scene where Duggan was shot dead, the IPCC said.
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However, a report in the Guardian on Monday said that initial tests by the National Ballistics Intelligence Service on the bullet found lodged in the police radio suggested that the bullet fragments were from police-issue ammunition, meaning they could not have been from a weapon fired by Duggan, casting doubt on claims that he was killed in an exchange of gunfire.
The IPCC said it would not comment on the Guardian report until all ballistics and forensic tests were complete.
Why did the police want to arrest him?
Trident officers, backed up by a CO19 detachment -- the Metropolitan Police's specialist gun unit -- were conducting a "pre-planned" operation to arrest Duggan. According to numerous media reports, Duggan was a suspected north London gang member who went by the street name "Starrish Mark."
What happened next?
On Saturday evening at around 5.30pm local time about 120 people, including members of Duggan's family and community workers, marched to Tottenham police station in north London, only a short distance from the scene of the shooting.
The march was peaceful according to reports, with protesters calling for "justice" and an investigation. Local roads were closed and traffic diverted.
About two hours later violence erupted, with gangs of youths attacking police cars, buses, shops, banks and other buildings. There was widespread looting in and around Tottenham.
What sparked the rioting is still unclear but police said: "We believe that certain elements, who were not involved with the vigil, took the opportunity to commit disorder and physically attack police officers, verbally abuse fire brigade personnel and destroy vehicles and buildings."
Why did the riots spread to other parts of London and the UK?
Police say the subsequent riots in other parts of London and the UK are copycat events that have little or nothing to do with the death of Duggan.
On Monday evening rioting had taken place in several London locations, including Battersea in south London, Ealing in the west and Hackney in east London. Disturbances were also reported in Birmingham in central England, Bristol in the southwest and Liverpool in northwest England.
On Sunday evening and in the early hours of Monday, rioting and looting was reported from several other parts of London, including Brixton in south London, Enfield in north London and Oxford Street in central London, the capital's main shopping district.
Are there enough police officers?
A video report from Battersea in south London on Monday evening showed gangs of youths roaming the streets, smashing and looting shops with apparent impunity. The Sky News reporter who shot the scenes on his mobile phone said he could not see a single policeman. There were similar reports from other parts of London leading to claims that there were not enough police to keep the peace.
According to the Metropolitan Police, 16,000 police officers will be on duty in London during the next 24-hour period. They also announced that all police leave had been cancelled.
The head of London's Metropolitan Police has called for all Special Constables -- volunteer police officers -- to report for duty.
What options do the police have to quell the unrest?
The police introduced special powers in four areas of London on Sunday -- Lambeth, Haringey, Enfield and Waltham Forest -- allowing stop and search without reasonable suspicion in a bid to keep rioters off the streets.
In theory, parliament could invoke powers to implement curfews, use water canons or even call in the armed forces.
However, senior politicians and police officers have said that these options are unlikely to be used unless the situation got significantly worse.
In 1981 police used CS gas for the first time to control civil unrest in mainland Britain during the Toxteth riots in Liverpool, northwest England.
Was social media a factor?
London's Deputy Assistant Commissioner Steve Kavanagh said that smart phones and social networks like Twitter had been used by criminals to liaise. "It's a group of individuals using modern technology to cause chaos," he said.
Other reports say BlackBerry's messaging service was a popular means of communication to spread news about the violence.
Are there any parallels with the 1985 Tottenham riots?
Only superficially, but some might argue that today, as in 1985, there is a racial element to the troubles.
In 1985 Floyd Jarrett, who was of Afro-Caribbean origin, was stopped by police near the Broadwater Farm estate in Tottenham on suspicion of driving with a forged tax disc.
A few hours later officers raided the nearby home of his mother, who collapsed and died during the raid. Her family said she was pushed by the police, a claim they deny. Rioting erupted shortly afterwards. Like the recent troubles, it was a protest outside Tottenham Police Station which sparked the 1985 conflict.
Police officer Keith Blakelock was stabbed to death by a gang during the riots as he tried to protect fire crews.
What about the riots in London and the UK last year?
They were student riots against tuition fee rises, although they were also marred by violence.
The IPCC is conducting an investigation. Colin Sparrow, deputy senior investigator for the IPCC, told an inquest into the death at north London Coroner's Court heard on Tuesday that their "complex investigation" could take four to six months.
The IPCC commissioner said in a written statement: "[We are] investigating not only the actions of the officer firing the shots but also the planning, decision making and implementation of the police operation. Our lines of enquiry include the bullets fired and any firearms used and recovered."