HALIFAX -- A review into how Nova Scotia police and prosecutors handled the high-profile Rehtaeh Parsons case says the investigation took too long and mistakes were made, but it was reasonable for the Crown to conclude that sexual assault charges should not be laid.

Parsons was 17 when she taken off life-support in April 2013 after attempting suicide.

Her tragic case attracted national attention when the young woman's family alleged she had been sexually assaulted in November 2011 when she was 15 and bullied after a digital photo of the alleged assault was passed around her school. The case and a number of other high-profile cyberbullying cases sparked a national debate about online harassment and changes to provincial law and the Criminal Code.

At the time of the girl's death, police said they had looked into the allegations of sexual assault and an inappropriate photo, but concluded there weren't enough grounds to lay charges after consulting with the prosecution service.

That led Parsons' parents to organize demonstrations that alleged police and prosecutors weren't doing their jobs.

The independent review released Thursday, led by former Ontario chief prosecutor Murray Segal, concluded that the initial police investigation, which lasted almost a year, took too long and was marred by human errors.

However, the review also found that the Crown's advice to a police investigator not to lay sexual assault charges was correct.

"While I find that more attention could have been given to the allegations ... the Crown's position, in view of the many evidentiary challenges in this case, was not unreasonable," Segal said in his report.

Even though there was a photo of the alleged offence, there were other pieces of evidence that weakened the case, the report says. There may have been sufficient grounds to believe a sexual assault occurred, but there was no realistic prospect for conviction, Segal concluded.

The report says the Crown identified inconsistencies between two statements Parsons gave to police. As well, there were inconsistencies with a statement given by a witness and various text messages.

The Crown also considered that due to her intoxication at the time, Parsons had little or no recollection of large portions of what happened that night in November 2011 at a home in Eastern Passage, N.S.

"Both the credibility and reliability concerns raised by the Crown prosecutor were not fanciful or based on personal opinion, but rather grounded on some objective facts collected by the police," the report says.

"These primarily went to the Crown's ability to prove lack of consent to the sexual activity at the time in question."

Parsons' father, Glen Canning, could not be reached for comment but he issued a statement on his blog Thursday saying that his daughter had lost faith in the justice system before she died.

"There is no excuse for someone so young to lose faith like that," the statement says.

"Nothing can bring her back and all I can wish for now is that her death was not in vain ... I'm tired of fighting. Hopefully, today will help heal the bitterness and anger and for the first time in years I can look ahead instead of behind."

Police acknowledged the shortcomings and offered an apology for the mistakes Segal identified.

"We apologize and we remain committed to addressing the issues and recommendations so we continue to progress," said acting Chief Supt. Dennis Daley of the RCMP.

"We have acknowledged some shortcomings that we take responsibility for. Will we improve? Yes ... we will improve."

Daley and Chief Jean-Michel Blais of Halifax Regional Police didn't get into specific failures, but said they have improved the training of officers investigating sexual assault cases.

Soon after Parsons' suicide, Prime Minister Stephen Harper addressed the issue in the House of Common and Nova Scotia introduced the country's first anti-cyberbullying law, which was followed by changes to the Criminal Code that made it an offence to distribute intimate images of someone without their consent.

Segal's report, which makes 17 recommendations, also found that the decision not to lay child pornography charges was an error.

A police investigator was told by a Crown attorney that the offence could not be prosecuted because it was not possible to tell from the photo that the persons involved were under age. That advice was incorrect because it was based on a misunderstanding of the law, the report says.

Segal told a news conference that other factors should have been considered at the time, including the fact that the young people in the photograph knew each other and were probably aware of each other's age.

As for errors that police made, the report says Parsons gave an unrecorded statement to a police officer before the case was handed to an investigator from the sexual assault unit, who conducted a second interview, which was a lapse in protocol.

Because of Parsons' young age, she should have been interviewed only once, alongside a social worker from the Department of Community Services.

A week after Parsons died, police reopened their investigation after receiving what they said was new information.

In August 2013, child pornography charges were laid against two young men, both 18 at the time.

A 20-year-old man pleaded guilty to distributing a sexually graphic image of Parsons. Another 20-year-old man pleaded guilty to making child pornography. Both men were youths at the time of the offences and were charged under the Youth Criminal Justice Act, which means they cannot be identified.

When one of the men was sentenced in January, the judge hearing the case told court Parsons was drinking at a house party with the two other teens when one of the boys took a photo of the other having sex with the girl from behind as she vomited out a window.

In the photo, the boy is smiling for the camera and giving the thumbs-up sign.

Judge Gregory Lenehan said Parsons did not know the photo was being taken and did not give consent for it to be shared.

The motivation for sharing the "sexually degrading" photo could have been to brag about a sex act, to embarrass Parsons or both, the judge said, adding that the accused stole her dignity, privacy and self-respect.