Sgt. Scott Shannon led the final investigation into how the military handled the life and death of Cpl. Stuart Langridge.
But his conclusions — that no one in the military broke any rules in their dealings with Langridge or his family — are part of a continuing inquiry at the Military Police Complaints Commission.
The inquiry was called following three years of what Langridge's family called flawed and biased investigations into what happened in the days before and after Langridge killed himself in 2008.
But during a day-and-half of often-combative testimony at the inquiry, Shannon insisted his review was thorough and detailed.
At issue is the refusal of the military to tell the family there had been a suicide note; how officers decided who would plan the funeral; and how they treated Langridge's continuing struggles with addiction and possibly post traumatic stress disorder.
Shannon, who has conducted 109 investigations in his six years with the National Investigative Service, had been tasked with reviewing prior investigations into those problems.
Langridge hanged himself in his Edmonton barracks following prior suicide attempts and hospitalization and treatment for addiction.
In the days before his death, he had been on strict supervision on the base in what his family and friends considered a suicide watch.
At one point, the inquiry heard that he said he'd rather kill himself than return to his unit.
But Shannon said that statement was among the facts he considered irrelevant as he reviewed whether the military's treatment of Langridge constituted either criminal negligence or violation of military law.
The possibility of criminal charges had been raised by Langridge's mother and stepfather, Sheila and Shaun Fynes.
Nor did his addictions or mental-health issues factor in to determining whether the threshold of criminal negligence on the part of the military was met, the inquiry heard.
It's impossible to pin responsibility for a suicide, Shannon said.
"I'm not Cpl. Langridge. He's the only person who can answer that question," Shannon said.
As for the specific complaints of failure to carry out military duties in the wake of Langridge's suicide, Shannon said the military followed all the existing rules and procedures.
He said when they decided Langridge's longtime girlfriend was his next of kin, they did so appropriately, based on the "customs of society" that consider a spouse to be someone's next of kin.
He told the inquiry that to arrive at his overall conclusions he focused on available documents and transcripts from prior interviews.
"The evaluation of the documents speak louder than any statements made by an individual four years after the fact," Shannon said.
Shannon said he drew his understanding of the facts of the case from the hundreds of pages contained in the files, as well as his prior experience as an investigator.
But he was grilled by commission counsel, as well as lawyers for the Fynes family and the commission chair, as to how he arrived at his conclusions.
"What if your interpretation of a document, by your interpretation ... what if you were wrong?," Glenn Stannard, the commission chair asked.
Shannon acknowledged that if had he been wrong, the rest of his investigation was flawed but said he had all the information he needed.
He said his investigation wasn't about whether the military's decisions in the Langridge case were right or wrong but whether they broke any rules.
He called allegations of bias in his investigation unfair, noting that he worked alone and often on his personal time on the investigation.
"I have lived up to my obligations and my promises to Mrs. Fynes," Shannon said.