Definition: Generate an appropriate title for the given text. The generated title must be short and include the main topic of the text. The preferred titles are under fifteen words.
Input: Twenty-two people were killed and hundreds more injured when Salman Abedi detonated a bomb in May 2017. His brother Hashem was jailed for 55 years in August for helping plan the atrocity. A barrister representing British Transport Police at the public inquiry said it was "obvious" they had help. 'Mass murder' "What of the other potential murderers?" asked Patrick Gibbs QC during his opening statement on behalf of British Transport Police (BTP) at the inquiry sitting at Manchester Magistrates' Court. "We don't yet know their names." He cited the "intricate, lengthy and carefully planned preparations" of the brothers, detailed earlier in the inquiry and during Hashem's trial. "It will be obvious, I suggest, to all of us that those brothers did not act alone. "They must have received technical help, financial help and training and support from other people," Mr Gibbs said. "Other people must have known or at least suspected what they were up to and those other people are at large." Mr Gibbs suggested the "mountain" of money spent on the inquiry would be worthwhile "if one or more of those accessories to mass murder... can be brought to justice". He said although BTP was responsible for policing the arena, as it is on the site of Manchester Victoria railway station, it had no intelligence about the bomber, who was known to security services and counter-terrorism police. Despite Abedi's three trips to the arena in the days before the attack on "hostile reconnaissance" a young man with a backpack at a railway station was not unusual, the inquiry heard. Two BTP officers had missed Abedi "by a matter of seconds" at 20:48 when they checked on the toilets while the bomber was in there with his backpack, Mr Gibbs said. And at the time BTP officers were in the foyer - where the bomb was detonated at 22:30 - Abedi was "out of sight" hiding as best he could in a mezzanine area for an hour before the attack. 'Carousel of blame' Four BTP officers at Victoria Station immediately ran to the scene, helping evacuate the dying and injured, Mr Gibbs said. The "overall" assessment of BTP's response was "extremely good", he said, and he had "nothing negative" to say about other organisations, such as Greater Manchester Police, fire or ambulance services. However, he described a "carousel of blame" which he said had been "sent spinning" by Jonathan Laidlaw QC, representing Showsec - the company employed to provide arena security. Mr Laidlaw said it was "not a question of buck-passing" but stated that Showsec provided crowd management services. He said security was only one element of its remit and it mainly employed students part-time so there were limits to what could be expected in terms of a counter-terrorism deterrent. It was also said the arena's foyer is a public thoroughfare with access to the railway station. SMG, operators of the arena, admitted there were "shortcomings and "inadequacies" in its risk assessments but Andrew O'Connor QC said SMG did have security measures in place that were "at the time considered generally appropriate to mitigate terrorism risk". Why not follow BBC North West on Facebook, Twitter and Instagram? You can also send story ideas to northwest.newsonline@bbc.co.uk

Manchester Arena Inquiry: Bomb plotters 'still at large'