Allegations that MacIntosh sexually abused children first surfaced in 1995, but he wasn't brought back to Canada until 2007, a year after Ottawa formally asked India to extradite him.
The review said Crown attorney Richard MacKinnon failed to follow up promptly as the case moved along because of his Port Hawkesbury office's heavy workload and the volume of the other cases he was handling in court.
It also singled out the oversight by Cape Breton's chief Crown attorney at the time, Kenneth Haley.
"It is apparent from our records that the chief Crown attorney for Cape Breton region did not play an active role in managing the progress of this file," states the report.
Both MacKinnon and Haley are now judges.
But perhaps the heaviest criticism is reserved for Ottawa's role in a prolonged extradition process that saw MacIntosh's passport renewed in 1997 and in 2002, despite the fact there were outstanding charges and a warrant for his arrest. The RCMP had also requested that Immigration and the Passport Office red flag MacIntosh in the event he re-entered Canada.
The report said the federal Justice Department has never explained why the passport wasn't revoked.
Martin Herschorn, director of public prosecutions in Nova Scotia, said once the passport was renewed officials were obligated to follow the formal extradition process.
"Efforts to have his passport revoked were inexplicably halted," said Herschorn. "Had his passport been revoked or not renewed this may have forced his return to Canada much earlier or facilitated his arrest by Indian authorities."
But ultimately, Herschorn said his department failed the nine men who alleged they were assaulted by MacIntosh in the 1970s.
"We know that the role we played in the delay is unacceptable and we know that letting these courageous men down is unacceptable," he said.
Nova Scotia Justice Minister Ross Landry issued a statement apologizing to the complainants in the case.
"I want the victims and all Nova Scotians to know that we have made changes provincially and will advocate for changes federally to ensure no one has to experience what you have lived through," said Landry.
Landry said he has sent a letter to three federal ministers including Justice Minister Rob Nicholson outlining his concerns and requesting they conduct their own internal reviews into Ottawa's role in the delay.
In an email, Justice Canada spokeswoman Carole Saindon said the department will review Nova Scotia's report, while its International Assistance Group, which is responsible for extradition, will review its processes.
Nova Scotia's opposition parties said the internal review isn't a substitute for a public inquiry or independent review.
Liberal justice critic Michel Samson said the report is disingenuous in laying blame at the feet of the Crown in Port Hawkesbury and doesn't explain why it took another three years to bring MacIntosh to trial once he was back in Nova Scotia.
"This obviously should have been getting all the attention it required from the public prosecution in Halifax to ensure necessary resources were being applied," said Samson.
The review by the Public Prosecution Service was ordered after the Supreme Court upheld a lower court's decision to quash 17 sexual convictions against MacIntosh. The Nova Scotia Court of Appeal threw out the convictions against MacIntosh in December 2011 because of the delay.
MacIntosh was living in India and employed as a consultant when the allegations first came to light.
Brian Casey, one of MacIntosh's defence lawyers, has previously said his client didn't try to hide from Canadian authorities during his time in India. Casey said the police officer in charge of the case had MacIntosh's address as early as February 1995 and that his client lived within three blocks of the Canadian High Commission in New Delhi, where he went regularly to renew his passport.
He said MacIntosh had given his address and telephone number to the Canadian government and was living openly under his own name.
In a separate internal review, the RCMP says it assigned one officer in Port Hawkesbury to the case in January 1995 when the first complainant came forward in British Columbia to allege he had been sexually assaulted, which was followed about a month later with a second complaint.
"The investigator would have been working on numerous criminal investigations at any given time," the report says. "With ongoing files being created given a range of other daily calls for service, at the detachment level, the MacIntosh file would have been investigated and prioritized consistent with the many requests for services that RCMP respond to. RCMP laid charges in relation to both initial victims within eleven months."
The RCMP says it did find a lapse in its documentation of the file between June 2003 and 2004 because of what it called "human resource pressures" in the district that was handling the case.
When he was returned to Canada, MacIntosh faced two trials, each dealing with a separate group of complainants.
The former Cape Breton businessman was convicted of molesting four boys. The convictions included eight counts of indecent assault and nine counts of gross indecency.
MacIntosh, who spent a year in custody and another four years of house arrest, was released in December 2011 when the court of appeal issued its ruling.
The Crown blamed MacIntosh for the delays when the convictions were overturned.
Note to readers: This is a corrected story. A previous version misspelled the last name of Martin Herschorn.Suggest a correction