Sharia law is a religious law forming part of the Islamic tradition. It is derived from the religious precepts of Islam, particularly the Quran and the hadith. 

According to sources, 28-year-old Usman Khan lived in Pakistan for one term before turning into a terrorist for the first time.

Met Police Assistant Commissioner Neil Basu said he was known to the authorities and had been convicted for terrorism offenses in 2012.

Basu said, "We are now in a position to confirm the identity of the suspect as 28-year-old Usman Khan, who had been residing in the Staffordshire area. As a result, officers are, tonight, carrying out searches at an address in Staffordshire."

"This individual was known to authorities, having been convicted in 2012 for terrorism offences. He was released from prison in December 2018 on licence and clearly, a key line of enquiry now is to establish how he came to carry out this attack," he said.

Khan, who was shot dead by security forces during Friday's attack, pleaded guilty in 2012 for preparing acts of terrorism as a member of an al-Qaeda-inspired terrorist cell that had planned to attack the London Stock Exchange, sources said.

"He originally received an indeterminate sentence for public protection but this was quashed at the Court of Appeal in April 2013 and he was given a 16-year jail term," a source said.

Pakistan origin:

Khan left school with no qualifications after spending part of his late teens in Pakistan, where he lived with his mother when she became ill.

On his return to the UK, he started preaching radical Islam on the internet and attracted a significant following, said sources.

Kashmir connection:

Khan had planned to use land owned by his family in Kashmir to build a terror training camp next to an existing mosque, in the hope of establishing Sharia law in the region, sources said.

Friday: London left shocked

The incident took place on Friday afternoon just hours before city workers end their work and head to the station for their train home.

London Bridge is one of the capital city's main transport hubs with thousands of commuters travelling through it daily.

The incident left two people killed and three others hurt, police said.

London Bridge attack in 2017:

At least eight people were killed and several others were hurt when an attack took place on the bridge on June 3, 2017.

Terror group ISIS had claimed responsibility for the incident.

UK's terrorism threat level downgraded:

The latest incident occurred just days after the UK government downgraded the terrorism threat level from "severe" to "substantial".

The UK's terrorism threat level has been downgraded from "severe" to "substantial", the Home Office said as reported by BBC on Nov 4.