Theresa May (as home secretary in charge of the intelligence services) and David Cameron, prime minister at the time, are responsible for the Arena attack and ensuing deaths. May oversaw the freedom for Libyan militants opposed to Gaddafi to travel to and from Libya with the assistance of our intelligence services. Many of these settled in Manchester and were all known to MI5 and MI6. They were provided with funds by the intelligence services and material assistance.
May is directly and personally responsible for the deaths and the scores of people injured in the Arena attack.