The information was revealed in a written response to 101 questions sent to investigators by Yassar’s dad, Mohammed Yaqub.
Mr Yaqub, who has hired top lawyer Michael Mansfield QC, put a series of detailed questions to the Independent Police Complaints Commission (IPCC).
The commission is carrying out an investigation into the circumstances of Yassar’s death on the motorway slip road at Ainley Top on January 2 this year.
Now the IPCC has responded to all 101 questions, though some they have said they cannot answer at this stage.
Mr Yaqub said that some 11 months on he could not understand why the officer who shot his son had not been interviewed.
“I cannot believe that the IPCC have not interviewed the officer who shot Yassar. Surely that is the first thing that should have happened?
“We asked a straightforward question about whether the officer had been interviewed – and the reply was ‘not yet.’ I don’t know what they are waiting for.”
Yassar, 28, was in the front passenger seat of an Audi that was stopped by police in a pre-planned operation on the slip road.
He was shot through the windscreen of the car and later officers recovered a “non-police issue” handgun from the footwell.
The IPCC previously said that “initial accounts and additional detailed accounts” had been taken from all officers at the scene but there was no mention of an interview.
Mr Yaqub has written to Prime Minister Theresa May asking for her support and he has also contacted several local MPs and prominent national MPs.
He has received a reply from the Prime Minister’s office and says he has the support of many MPs in his campaign for justice.
“There’s been a lot of progress and we have a lot of support from MPs,” said Mr Yaqub. “I am hopeful that one of the MPs who are supporting us will ask a question at Prime Minister’s Question Time.”
Mr Yaqub and wife Safia continue to grieve for their son and he added: “I cannot let it go or forget about what happened.”
The family have attended events organised by the United Families and Friends Campaign, a coalition of those affected by deaths in custody, and Mr Yaqub has twice been to No10 Downing Street.
Mr Yaqub said there would be a religious ceremony to remember Yassar on January 1 with a large event planned for Huddersfield the following day, to mark the first anniversary of his death. More details will be revealed later.
In a statement an IPCC spokesman said: “We have not yet required an interview with the firearms officer who shot Mr Yaqub – who has provided comprehensive statements to investigators – but this may be necessary at a later stage as the investigation is not yet complete.”