ST. JOHN'S, N.L. -- The grieving daughter of Don Dunphy still doesn't know why a Royal Newfoundland Constabulary officer went alone to her father's home on Easter Sunday 2015 for a meeting that turned deadly.

The Mounties said Tuesday an independent review supports their decision to lay no charges in the shooting of the 59-year-old man killed by a member of former premier Paul Davis's security unit.

The Mounties did not release the full report or any recommendations.

But Meghan Dunphy, Don's daughter, said in a statement that members of the civilian-led Alberta team which reviewed the RCMP probe told her in a verbal briefing Tuesday that evidence was lost due to police "errors" and "local inexperience." Those mistakes weren't enough, however, to undermine the outcome.

Dunphy said she was told that retired judge David Riche, who was named to independently observe the RCMP investigation, wrote a separate report raising concerns about the shooting itself.

The lone officer was in RCMP jurisdiction when he went to Dunphy's home in Mitchell's Brook, about 80 kilometres southwest of St. John's, to check out a perceived threat on social media.

The RCMP later reported the plainclothes officer was working a regular shift and had assessed the risk as low before visiting the reclusive man. The Mounties said he was invited in for a 15-minute talk that suddenly escalated before Dunphy aimed a rifle at him.

A loaded .22-calibre rifle was found on the floor of the home next to Dunphy's body, the RCMP reported.

The Mounties concluded their investigation in January. Justice Minister Andrew Parsons then asked the Alberta Serious Incident Response Team (ASIRT) to assess it.

"They reviewed our investigation and went through every part of it and said that it was thorough, unbiased and did not lack objectivity," RCMP Sgt. Pete McKay said Tuesday. "(It) was complete and followed best practices of major case management."

McKay said the force would not release the report, discussing only the findings, so as not to taint a public inquiry promised as the Liberals won power last fall from the previous Progressive Conservative government.

Parsons said Tuesday he hasn't seen the complete review or its recommendations but confirmed the inquiry will now move ahead as soon as possible. He stressed it would be inappropriate for him to interfere or direct police operations.

Parsons said he still has confidence in local police forces but shares the frustration of not knowing -- more than 16 months later -- even basic facts of what happened that day and why.

The tragedy also highlights a major gap that police officers themselves want filled, Parsons said outside the legislature.

"We need our own civilian oversight operation here to avoid these situations where ... one force is investigating the other. It doesn't carry great weight with the public."

Meghan Dunphy's statement said she hasn't seen the full RCMP file, the judge's report or the ASIRT report, but said she was pleased Parsons has committed to an inquiry.

"She hopes she will get answers to her many unanswered questions," it said.

In a letter to the Justice Department, ASIRT executive director Susan Hughson notes her team found "some minor shortcomings," in the RCMP probe, and had "some minor observations and recommendations regarding aspects of the investigation," but none of them brought the overall probe into question.

Hughson also emphasized her team's role as reviewer, not investigator.

"ASIRT has not been asked to provide an opinion on whether the use of lethal force was appropriate in the case," Hughson wrote.

Family and friends in the tiny St. Mary's Bay community have asked why an officer unknown to Dunphy would go alone to investigate perceived Twitter threats. They described Dunphy as a former heavy equipment operator who was severely injured on the job as a younger man.

The frequent Twitter user called himself "a crucified injured worker from NL Canada where employers treat (the) injured like criminals."

Dunphy had lived alone for years after the death of his wife in the tree-shrouded home where he died. He was close to his daughter, Meghan, who has questioned the police investigation almost from the start.

Former premier Davis, who was a member of the Royal Newfoundland Constabulary before entering politics, has confirmed his staff told police about potentially threatening tweets two days before Dunphy was killed. Davis said that, at the time, he was not aware of the Twitter posts until after the fatal confrontation.

Dunphy had commented on Davis's official Twitter account and that of Sandy Collins, the former minister for child, youth and family services.

He referred to how God would get politicians who ignored and laughed at the poor -- before they could collect pensions "they didn't deserve."

"I won't mention names this time," Dunphy posted, "2 prick dead MHAs might have good family members I may hurt."

The content of the tweets sparked intense debate about whether they were even meant as a threat.