Omar Abdel Hamid El-Hussein

He was a visitor to the al-Faruq mosque in Nørrebro, a mosque whose imam in 2017 posted a video of his sermon on YouTube which encouraged the murder of Jews.

Amid heavy security a major court case against the four defendants began in Copenhagen Municipal Court in March 2016. On the first day of the court case, the court ban against naming the four was lifted by the judge. Some Danish and international media chose to name the four defendants, some chose not to. All four are affiliated with or members of immigrant criminal gangs in Copenhagen and have extensive criminal records covering minor crimes such as theft to more serious convictions for armed robbery, assault, attempted murder and possession of illegal and dangerous weapons and explosives. The four were named as; 26-year-old Bhostan Hussain, 31-year-old Mahmoud Rabea, 23-year-old Ibrahim Abbas, and 20-year-old Liban Salesian Elmi. The court case has been marred by interruptions and outbursts from Rabea, who amongst other things called the female judge 'a pig', 'a nazi-whore' and asked her to perform fellatio on him. These insults uttered in a public court house are punishable by Danish law with up to six months in jail and according to Danish media Rabea has been charged for the offences.

On 14–15 February 2015, three separate shootings occurred in Copenhagen, Denmark. In total, two victims and the perpetrator were killed, while five police officers were wounded.

Swedish cartoonist Lars Vilks had been the subject of death threats from Islamic extremists in the wake of the controversy over his drawings of Muhammad in 2007. On 14 February 2015 at 15:00 CET, an event titled "Art, Blasphemy and Freedom of Expression" (Danish: Kunst, blasfemi og ytringsfrihed) took place at Krudttønden cultural centre at Østerfælled Torv in the Østerbro district of Copenhagen, the capital of Denmark. The debate, organized by the Lars Vilks Committee, was scheduled to include discussion on the attack in January against the French satirical weekly Charlie Hebdo.

At 00:50 on 15 February 2015, a second shooting took place at the Great Synagogue on Krystalgade in central Copenhagen. A bat mitzvah ceremony attended by 80 people was taking place there.

In November 2013, the police wanted El-Hussein for an indiscriminate knife attack on a man riding a suburban train in Copenhagen. He was arrested in January 2014, and remanded in custody. The prison had concerns about his bizarre and fanatical behaviour in prison and filed report to the Danish Intelligence Service in September 2014, as they found that he had changed behaviour and become "extremely religious". In December 2014, he was sentenced to two years in prison. He was, however, released on 30 January 2015, after having been imprisoned for one year (11 months in custody before sentencing and 1½ month after).

Dan Uzan, a 37-year-old volunteer security guard, was killed in the Great Synagogue attack. At the time, a bat mitzvah ceremony was taking place in the synagogue, with about 80 people in attendance. Uzan, the son of a Danish mother and Israeli father, was Jewish, and his family are active members of the Copenhagen Jewish community. Uzan was buried at Copenhagen's Jewish Western Cemetery on 18 February 2015, with Prime Minister Thorning-Schmidt among those attending. Police snipers guarded the funeral.

On 16 February 2015, the police reported that one of the injured officers had received a shot to the chest but his bulletproof vest prevented it from seriously injuring him.

The first shooting took place on 14 February at a small public afternoon event called "Art, Blasphemy and Freedom of Expression" at the Krudttønden cultural centre, where an armed gunman killed one civilian and wounded three police officers. 30 to 40 people attended the event, amongst whom were the Swedish artist Lars Vilks, who was among the key speakers, and François Zimeray, Ambassador of France in Denmark, who opened the seminar with his speech just before the attack took place. Lars Vilks is often described as the main target because of his drawings of Muhammad. The second shooting took place later that night (after midnight, and, therefore, on the 15th), outside the city's Great Synagogue in Krystalgade. A gunman killed a young Jewish man on security duty during a bat mitzvah celebration, and wounded two police officers. Later that morning near Nørrebro station, police tracking the suspect shot and killed a man, after he opened fire on them while he attempted to enter a residential building under police surveillance. The man was identified as Omar Abdel Hamid El-Hussein, who police said was responsible for both attacks.

El-Hussein spent most of his childhood in Mjølnerparken in Nørrebro. When he was in primary school, his parents divorced and he lived with his mother. When he was twelve years old, his mother sent him to Jordan where he spent three years. Upon returning to Denmark he had problems in school. He for a time attended a Higher Preparatory Examination at a Danish Voksenuddannelsescenter (VUC) in Hvidovre. He became a member of the Brothas gang in Mjølnerparken, and was sentenced twice for violence, possession of an illegal weapon, and hashish possession before 2013.

On 20 February around 600–700 people, the majority of whom were young Muslim men, attended the burial of the killer who was interred at the Muslim burial site in Brøndby. The Friday prayer at the mosque, which had been followed by a brief ceremony for the gunman, drew an estimated 3,000 people, reported by mosque guards to be double the usual number, leading many to have to stand outside the mosque during the sermon.

Omar Abdel Hamid El-Hussein (Arabic: عمر عبد الحميد الحسين ‎; 11 September 1992 – 15 February 2015), a 22-year-old man, was identified as the suspected shooter. He was born in Vordingborg, Denmark, to Jordanian-Palestinian parents, and grew up in Copenhagen and in Jordan. Danish police previously stated that the subject was 22 years old and well known to the Danish intelligence services.