The wife of a former volunteer fire chief killed during July’s assassination attempt on Donald Trump in Butler, Pennsylvania, has told the BBC she is furious about the security failures that led to her husband’s killing by a rooftop gunman.

Corey Comperatore was shot dead after diving on members of his family to protect them as 20-year-old Thomas Crooks opened fire at the former president.

His wife Helen said she hasn’t been able to stop replaying the events of the day in her mind.

"I see it every time I close my eyes, and probably will for a long time" she said.

"I'm angry because there were a lot of mistakes made that day, and it didn't have to happen,” she added.

Helen Comperatore spoke exclusively to the BBC just days before Trump is set to return to Butler and the site of the shooting.

The home she shared with Corey in Sarver is less than 20 miles (32 km) from the Butler rally site, and close enough to the volunteer fire station where he worked for decades that when its sirens blare they can be easily heard.

Trump will hold a rally on Saturday on the same grounds where he was shot in the ear, before defiantly raising his fist and mouthing “Fight!’, in what has become a defining image of his campaign.

Multiple members of the Comperatore family will be Trump's guests at this weekend's rally, including Helen.

Corey Comperatore, 50, was killed in the July shooting and two other people suffered “life-changing” injuries: 57-year-old David Dutch and 74-year-old James Copenhaver.

A Secret Service internal review has since identified a litany of security failures that day, including poor planning and a communication breakdown.

Corey, who was an ardent supporter of the current Republican presidential candidate, had been excited for the July rally, his wife said.

"He just liked how [Trump] got things done, and that he wasn't a politician and he didn't talk like one."

She said they believe Trump understands the lives of people like them, in places like Butler, a working-class community just north of Pittsburgh.

At the rally, the family ended up by happenstance in the bleachers between Trump and the shooter.

They'd taken time to eat beforehand and missed the opening to get a seat - to Corey's disappointment. But then a man came by and offered them a spot in the stands.

About six minutes into Trump’s speech, Crooks fired eight shots from a roof just outside the rally’s perimeter, one striking Trump’s right ear and one striking and killing Corey as he sheltered his family.

In the months before her husband was killed, the couple spent every weekend on their boat.

"We loved that time together," Helen said.

"We talked about everything. We made a lot of future plans on that boat. I knew a lot about Corey and what his wishes were, if anything ever happened to him."

The couple had known one another their entire lives - they began attending school together as kindergartners.

She said her husband often appeared straight-faced and serious, but behind the façade was a deeply kind and caring man.

"As soon as he smiled, you knew he was a good, good man," she said.

"He did anything for his community. He loved his kids. His kids were everything to him."

His two daughters, Allyson and Kaylee, are nurses and struggling to get back to work while they grieve their dad, Helen said.

She said now the questions of "What would he want me to do? What would Corey do?" help guide her.

"It's definitely a struggle. I realised I always knew he took care of me, but I never realised just how much. I just miss him," she said.

Corey Comperatore was honoured at the Republican National Convention (RNC) in July, with his helmet and coat displayed on stage as Trump spoke.

Helen said at the July rally, Corey had hoped - and joked - that Trump might call him on stage.

The family watched the RNC moment on television, after Trump told Helen about the planned tribute.

"And I just cried because I said he got his moment on stage with Trump," she said. "So, you know, it was kind of like a nice moment, but it was a sad moment at the same time."