Jihad Al-Shamie was arrested on suspicion of rape and on police bail at the time he launched a deadly knife and car attack on a Manchester synagogue, police have said.
Adrian Daulby and Melvin Cravitz were killed in the attack on Thursday, while three people remain in hospital.
Police believe that Al-Shamie may have been influenced by “extreme Islamist ideology” and said three more people, between 18 and mid-40s, had been arrested on suspicion of commission, preparation and instigation of acts of terrorism.
On Friday, families of the dead men paid tribute to their loved ones, hailing them as heroes who died saving others.
Al-Shamie, 35, was a British citizen of Syrian descent who was living in Prestwitch, Manchester.
Police said his name did not show up during initial searches of police and security service counter-terrorism records, but the head of Counter Terrorism Policing Laurence Taylor said: “At this stage, we believe Al-Shamie may have been influenced by extreme Islamist ideology.”
In a statement on Friday, Al-Shamie’s family said: “We fully distance ourselves from this attack and express our deep shock and sorrow over what has happened.
“Our hearts and thoughts are with the victims and their families, and we pray for their strength and comfort.”
People in Prestwich told the Al-Shamie was a weightlifting enthusiast who rarely spoke to his neighbours.
Mr Daulby, 53, and Mr Cravitz, 66, died in the attack after the attacker drove a car at members of the public before stabbing people on Thursday morning.
Greater Manchester Police said Mr Daulby was hit by police gunfire as they shot the attacker shortly after the alarm was raised.
Mr Daulby’s family, said he “lost his life in the act of courage to save others” and his final act “was one of profound courage and he will forever be remembered”.
Mr Cravitz, from Crumpsall, was working as a security guard at the synagogue.
In tribute, his family said: “He was so kind, caring and always wanted to chat and get to know people.
“He was devoted to his wife, family and loved his food. He will be sorely missed by his wife, family, friends and community.”
The Independent Office for Police Conduct (IOPC) said it would investigate the use of lethal force by firearms officers responding to the attack, which happened on Yom Kippur, the holiest day in the Jewish calendar.
Armed police accidentally fatally shot Mr Daulby, while worshipper Yoni Finlay was also shot by police leaving him serious injuries.
The investigation will focus on the “circumstances surrounding the fatal police shooting of Jihad Al-Shamie”, as well as “whether police may have caused or contributed to the death of the man later found to have suffered the fatal gunshot wound”.
Counter terror police also released more details about what happened in the run up to Thursday’s attack at the Heaton Park Hebrew Congregation synagogue.
In a statement released to the press on Friday, Mr Taylor said: “We have been told from witness accounts that a man was seen acting suspiciously outside the synagogue before he was confronted by security and walked away”.
At the time, the incident was not reported to police. Fifteen minutes later, “the individual returned in a vehicle and began his horrific attack,” Mr Taylor added.
Police are seeking warrants to further detain all six people now in custody, he also said. On Thursday, Greater Manchester Police said three other suspects – two men in their 30s and a woman in her 60s – had been arrested on suspicion of commission, preparation and instigation of acts of terrorism.
Rabbi Daniel Walker was leading prayers when his synagogue was attacked and described seeing “evil and hate” as a man began “body-charging the doors, throwing heavy plant pots, doing whatever he could to get in”.
Praising the quick-thinking of those at the synagogue, he told the : “I saw genuine heroism, I have to say, and people who ran to help others rather than running away. It was astonishing.”
Alan Levy, the synagogue’s chairman of trustees told ITV News, he heard Al-Shamie shouting “this is what they get for killing our children”, before “banging his knife into the glass, trying to get through”.