Shaun Fynes, in his second day of testimony before a public inquiry, said he believes his son's last communication was kept back to protect the military.
"My son had (post-traumatic stress disorder), he was in pain and he couldn't take it anymore," Fynes testified Thursday. "That was the truth of that note and that was part of the coverup."
The Canadian Forces National Investigative Service says it held on to the note because it was evidence in an ongoing investigation.
It acknowledges 14 months does not represent "expeditious" handling of the note, but has never explained why it needed to keep it beyond the first few days of the investigation.
"I am left to conclude it was not inept and it was a very calculated deception designed to protect the uniform from embarrassment," Fynes said.
The family has never received a formal apology regarding the note, although the military has conceded it was wrong to withhold it.
Fynes says when the family did finally receive the note, it was a photocopy, and they had to demand the original.
The Military Police Complaints Commission is examining whether the military investigation into Langridge's March 2008 death was biased.
At one point, as the family searched for answers, the military investigators refused to meet Fynes because they anticipated he might take legal action.
"It speaks to an attempt to protect the image and the brand," Fynes said. "It doesn't speak to police work — or my understanding of police work, or the independence of police work to conduct a fair and impartial investigation."
The family had not threatened to sue over the death, but had filed a statement of claim to recover money they felt was owed to their son's estate, Fynes added.
That claim was dropped.
Justice Department lawyer Elizabeth Richards challenged the notion that military covered up the suicide in order to avoid embarrassment, pointing to its role in catching serial killer Russell Williams, a former air force colonel.
"So you agree there are incidents and circumstances where military police do investigate senior leadership within the Canadian Forces and do lay charges?" she asked.
"And you're aware the National Investigative Service has been involved in (investigating) alleged drug use by members of the Canadian Forces?"
"I'd certainly hope so," Fynes answered.
"And that's something in fact you wanted investigated, and you'd agree with me that's something that might be embarrassing," Richards continued.
Langridge struggled with alcohol and drug addiction during the last few years of his life following tours of duty in Bosnia and Afghanistan.
He had five — possibly six — previous suicide attempts.
The military disputes the claim the 28-year-old veteran suffered from post-traumatic stress and blames his suicide on addictions and turmoil in his personal life.
The lawyer for the commission said it's been unable to find any medical report that indicates "a primary diagnosis" of PTSD, although some of the records suggest Langridge should have been examined further for the condition.
Richards pointed to medical records from several institutions which stated that Langridge suffered an alcohol-induced mood disorder, as well as alcohol and cocaine dependency.
"I suggest to you that in all the medical records, the medical professionals considered that the substance abuse was the illness," she said.
She also noted one report that said Langridge, while in civilian rehab, smuggled cocaine into the hospital.
"I will go to my grave believing my son suffered with PTSD because his behaviour changed so markedly," said Fynes.
Michel Drapeau, the lawyer for the parents, said regardless of whether there was a formal diagnosis of PTSD, the medical records show a young man in distress and they only underline that the military had an obligation to care for him.
The actions of the military in the days leading up to the death were put under the microscope with Fynes' testimony.
Prior to hanging himself in a barracks room, Langridge had spent 30 days in a civilian hospital, but was persuaded to return to the Edmonton garrison upon completion of his stay.
Fynes said his son expected to be admitted to a military hospital or treatment program, but instead found himself placed in barracks and treated as a "defaulter."
The military admits to placing Langridge on restrictions, which included menial tasks, such as shovelling snow.
His regimental sergeant-major told military police investigators that the young man was being given an opportunity to prove his worth as a soldier, according to transcripts already filed with the commission.
But Fynes said it "humiliated" the young man before his regiment — something that ultimately drove him to take his life.
The family demanded military police conduct a criminal negligence investigation, which did not happen.
At the end of Fynes' testimony, commission chair Glenn Stannard addressed both parents, reminding them that the watchdog agency doesn't have the jurisdiction to comment on what sort of medical treatment Langridge should — or should not — have received.
He expressed sympathy for their plight.
"We're here to rule on whether the military conducted a proper investigation," said Stannard.
"There are some of those issues that are in your heart and are upfront that you may not hear from us, but it's not because we don't care."