The family of the murdered MP, Sir David Amess, say they have yet to receive a response from the home secretary after calling for a meeting in the summer.
Wednesday marks four years to the day since Sir David, the Conservative MP for Southend West, was stabbed to death while holding a surgery in Belfairs Methodist Church in Leigh-on-Sea, Essex.
Sir David's daughter, Katie Amess, told the BBC: "We went back to Keir Starmer and he's just ignored us ever since, despite promising us that he would meet with us again if we weren't happy."
A Home Office spokesperson said: "We understand that the Amess family are still looking for answers and we take this incredibly seriously".
Sir David's killer, Ali Harbi Ali, is in prison for life. His trial heard he became radicalised online by the war in Syria and by Islamic State.
"This was a murder that struck at the heart of our democracy," Judge Mr Justice Sweeney said.
The Anderson Review into the government's de-radicalisation programme, known as Prevent, found this summer that "in the case of Ali Harbi Ali, there was a string of failures".
Lord Anderson said this was down largely to "human error".
Ali Harbi Ali had one meeting with someone from Prevent following a referral from his school. There was funding for seven sessions, but only one face-to-face meeting took place.
The Prevent Learning Review found this was down to poor communication and a failure to identify radicalisation.
He was dropped from Prevent in 2016. It was around this time Ali Harbi Ali bought the knife that he would use to murder Sir David five years later, taking the weapon on reconnaissance trips including six visits to the home of the then cabinet minister Michael Gove.
Anderson concluded that Prevent has professionalised, which "make it much less likely that human error of that kind will occur again."
The Amess family lawyers wrote to the home secretary in July outlining specific questions:
- Were any checks made with the school before exiting Ali Harbi Ali from Prevent?
- What did the security services know in the five years between Prevent and Sir David's murder?
- What social media checks were carried out?
- To access documentation and interview the individuals who dealt with Ali Harbi Ali a decade ago
- To find out why Ali Harbi Ali was assessed to be dropped from Prevent and who made that decision.
They are now calling for a full public inquiry.
"There's grief, there's trauma, and there's also anger as to why nobody is helping us get these answers," Ms Amess said.
"I don't understand why the government isn't fully behind finding out why this happened.
"My dad was their colleague for nearly 40 years. He was a great friend."
The Amess family has tried to get the inquest into Sir David's death re-opened.
The senior Essex coroner, Lincoln Brookes, found "no evidential basis to consider this attack was possibly preventable so many years and imponderables later".
He added: "It would be speculative to assume that national security services do, should or could, detect and track every Islamic State sympathiser."
In July 2024, Mr Brookes turned down their request to reopen the hearing.
He concluded: "The fact that the perpetrator's case was not handled as well as it should have been in Prevent does not of itself amount to any evidence that Sir David's death was possibly or probably preventable five years later had his case been handled better."
"One can only speculate."
A Home Office spokesperson said: "While we do not think a public inquiry would unearth any information that has not already been assessed, we have confirmed that we will further scrutinise all the reviews that have taken place over the last few years."
"We very much hope this will help the family to get the answers they deserve."
The government has indicated "a senior figure" will be appointed to look at the reviews.
The spokesperson added: "In the years since this cowardly attack, there have been several reviews asking how this could have been avoided, and we have seen significant improvements to the Prevent programme as well as stronger protections for MPs."
Downing Street did not comment further.