Salman Abedi was able to hide in CCTV blind spots in the foyer of Manchester Arena for nearly an hour before the attack on the audience leaving an Ariana Grande concert in 2017.
A report due to be published on Thursday into the Manchester Arena terrorist attack, which killed 22 people and injured hundreds more, is likely to find widespread failings in security at the venue.
Abedi detonated a bomb in May 2017 at the end of the US singer's concert.
Figen Murray, whose son Martyn Hett, 29, was one of the 22 people murdered, said she was anxious ahead of the publication.
She has been campaigning for Martyn's Law to ensure venues have action plans against such attacks.
At present it is up to venues to decide whether or not to adopt recommended security measures.
"I am slightly anxious to see what today brings in terms of the first report," she said on Twitter.
"Looking forward to hearing all the recommendations. So hope #martynslaw will be part of it as we worked so hard on this."
I am slightly anxious to see what today brings in terms of the first report. Looking forward to hearing all the recommendations. So hope #martynslaw will be part of it as we worked so hard on this. @CTCommentator @MrBrendanCox
— Figen Murray (@FigenMurray) June 17, 2021
An inquiry has been examining the circumstances surrounding the suicide bombing.
It is due to publish its first report into the security arrangements at the venue.
It is expected to focus on how Abedi was able to hide in CCTV blind spots in the foyer of the arena before the attack.
During the inquiry, the emergency services were criticised for their slow response, and bereaved relatives and survivors condemned delays in the treatment and evacuation of victims.
The Manchester Arena Inquiry is examining the circumstances of the attack and whether any opportunities to prevent it were missed.
The report is expected to look at British Transport Police, who were responsible for keeping people safe in the area on the night, and arena operator SMG and its contracted event security provider Showsec.
SMG, Showsec and British Transport Police have already accepted shortcomings in their risk assessments.
The inquiry was established by UK Home Secretary Priti Patel last year.
Suicide attacker Abedi, 22, died after detonating a rucksack bomb in a foyer of the arena.
His younger brother, Hashem Abedi, was convicted last year on 22 counts of murder, one count of attempted murder and one count of conspiracy to cause an explosion.
He was sentenced to a minimum 55 years in jail.
