Dr. William Lai, a Defence Department contract psychologist, heard from the military only once following the 28-year-old's suicide in March 2008.
"Somebody contacted me about having to appear before some sort of hearing," Lai told the Military Police Complaints Commission. "I don't remember exactly what the organization was called, but subsequently, I was told I was not required."
The commission is examining whether military police conducted a biased investigation into Langridge's death, a probe that critics have since alleged was predisposed towards exonerating the Canadian Forces.
Lai testified that Langridge, who'd served in Bosnia and Afghanistan, "likely" suffered from post-traumatic stress disorder, an assessment he based on a psychological questionnaire patients are required to fill out.
But he stopped short of describing his findings as a diagnosis, instead calling it a "working hypothesis" that required more interviews.
"I don't know if anything can be definitive," Lai said Tuesday under questioning by a commission lawyer. "There was a note to the effect that this particular patient should be investigated further in order to confirm, I suppose, the diagnosis."
The follow-up did not happen within the military system and Langridge eventually sought treatment for drug and alcohol addiction in a civilian hospital.
Lai was asked whether PTSD could be ruled out and he responded emphatically: "No, you cannot rule it out at this point."
Part of the problem in hammering down a diagnosis was that interviews conducted at the Edmonton garrison, Langridge denied having suffered from post-traumatic stress.
He was referred to Lai almost a year before his death, and met with the psychologist on at least two occasions.
Langridge expressed reluctance to talk about his experiences, according to Lai's report, and expressed fear about how a PTSD claim might impact his military career.
The issue of whether the young veteran suffered from the disorder is material to the claim by his parents that the military didn't get Langridge the help he needed and drove him to take his own life.
In its defence, the military has said it doesn't believe the PTSD claim and insisted Langridge took his own life as a result of his addictions and a personal life that was in turmoil.
The Military Police Complaints Commission has made it clear that it will not rule on the medical treatment the 28-year-old received — or did not receive— but will only look at whether military cops botched the investigation into his death.
The soldier who found the body also testified on Tuesday.
Roger Hurlburt, a former master corporal with the Lord Strathcona Horse Regiment, testified that there were rumours about Langridge, and his addiction battles, in the weeks leading up to his death.
As the regiment's duty driver on the day in question, Hurlburt was given no special instructions to keep an eye on his fellow trooper, and agreed with previous witnesses who denied that Langridge had been placed on a suicide watch.
Langridge took his own life after he was discharged from an Edmonton hospital and persuaded to rejoin the regiment, where he was placed on restrictions and told he'd get access to the bevy of military programs if his behaviour remained good.
His parents have described their son's treatment as humiliating and claim it sent him over the edge.