Speaking exclusively to The New Zealand Herald, Ms Crewe said she feared police were trying to protect their image.
Deputy Commissioner Rob Pope announced yesterday police would not reopen the case, but instead conduct a "thorough analysis and assessment of the Crewe homicide file in an endeavour to answer questions raised by Rochelle Crewe".
But Ms Crewe said last night the response from police was disheartening and the only "fair and honest" approach was to have the case reopened.
"I feel it is not adequate enough to just review what has already been done, as this may not be a wide enough net to capture what was previously left out of the original investigation, as well as a failure to examine all evidence that was available to them at the time," Ms Crewe said.
"I am very disappointed and I fear this is no more than a continuation of police seeking to avoid the truth and protect their image."
She was grateful for the public support since she broke her silence last week.
She said the failure of police to reopen the case at the time Arthur Allan Thomas was pardoned led to years of speculation, which was an "unnecessary injustice to my family".
"Had the police reopened the case after the pardon, perhaps they might have established who did this terrible thing to my mother and father [Jeannette and Harvey Crewe].
"Perhaps now, with witnesses dead and evidence destroyed by the police, there is not sufficient amount to prosecute, but I do not accept that this was the case in 1979.
"These past events erode my confidence in the police and the justice system."
Mr Pope said police had spoken to Ms Crewe some weeks ago and "understandably she has questions that she wants answers to".
"We will do our very best, taking into account the limitation of time and the availability and recollection of witnesses."
Mr Pope said Detective Superintendent Andy Lovelock, the top investigator in the Auckland region, had been appointed to lead a "detailed analysis of all information available and acquaint himself with all the details".
He emphasised it was not a re-opening or re-investigation of the case, which was "one of the most scrutinised in New Zealand history" after two court cases, a Royal Commission and the subject of several books.
Mr Pope urged anyone with information to contact the police.
Ms Crewe was just 18 months old when she was found crying in a cot, five days after her parents were last seen alive.
Arthur Allan Thomas - who spent nine years in prison for the murders before being pardoned - supported a new inquiry, as did his ex-wife Vivien Harrison.
Labour leader Phil Goff and Police Association president Greg O'Connor have both backed a new Crewe inquiry.
Mr Thomas was pardoned in 1979 after mounting public protest and the personal intervention of then prime minister Rob Muldoon.
The Royal Commission set up to investigate the case found Detective Inspector Bruce Hutton and Detective Len Johnston had planted the shellcase at the Crewe house to frame Mr Thomas.
Ms Crewe was critical of the decision of the Solicitor-general in the 1980s, Paul Neazor QC not to lay charges against the two detectives because he believed there was not enough evidence to justify a prosecution.
"For some bizarre reason, the Royal Commission inquiry finding did not amount to a strong enough basis to prosecute these perpetrators," Ms Crewe said.
"On the flip side, it was enough of a finding to have a man pardoned."
