"His body was not found until 23 September 2019. The delay in finding Mason's body meant that the cause of his death is unable to be determined. His family will never know what he died of."
Coroner Johnson is still looking into the circumstances of the student's death.
And at this stage, she says she cannot rule out that before his death, Pendrous was ill in his room.
Forensic pathologist Dr Christopher Lawrence performed a full post-mortem examination of Pendrous' body on September 24.
He noted decomposition and saw no injury or obvious cause of death.
There was no evidence of drugs or elevated alcohol levels in his blood and no identifiable pneumonia.
Lawrence stated that although the heart appeared normal he could not exclude some form of cardiac arrhythmia.
And because of the condition of the body it was not possible for Lawrence to assess some infective causes of death like influenza, pneumonia, myocarditis or meningitis.
There was a medicine for gastrointestinal upset in the room and Pendrous' body was found close to a heater which was on and the central heating was turned up, which Lawrence said could be consistent with a fever.
His medical opinion was that the cause of death was undetermined due to decomposition – which the coroner agreed with.
Coroner Johnson said it was "impossible" to know exactly when Pendrous died between August 26 and September 10.
"Given Dr Lawrence's evidence that he cannot exclude infective causes of death, I cannot rule out that before his death Mason was ill in his room," she said.
"This is an issue I will consider during my inquiry into the circumstances of Mason's death."
His death has raised questions about how a young student could go unnoticed and be holed up in his room without any red flags being raised.
An independent probe into the student's death on behalf of the university, overseen by former High Court judge Kit Toogood QC, is ongoing.
Last month's special hearing in Christchurch to verify Pendrous' date of death was told that Pendrous last used his swipe card to get into his university accommodation on August 12.
He was not seen coming or going for a fortnight, during which time his online activity "increased substantially".
The last time he's known to have spoken to anybody was on August 24 when he played an online war game with an old school mate in Wellington where they chatted over headphones.
UC Vice-Chancellor Professor Cheryl de la Rey said the university is "devastated" by the coronial findings released today.
She said the university is "committed to taking whatever action is necessary to make sure this never happens again".
While awaiting the findings and recommendations of the independent report, the university has already internally reviewed its processes and put in place further steps to ensure that appropriate pastoral care is available for all UC students in UC-affiliated accommodation.
"Our students, parents, whānau and schools can be assured that we take the health, safety and wellbeing of our students very seriously," de la Rey said.
From next year, it will not support the offering of semi-independent accommodation packages for first-year students. Apartment-style accommodation will only be available with enhanced support, which includes residential advisers living onsite at a 1:25 ratio.
UC says it will also introduce new measures in 2020 to further improve student support for all students on campus, not just those in residential accommodation, including an early alert system, a buddy system available to all first-year students, and an expanded induction programme covering support services, the student code of conduct, consent awareness, belonging/inclusiveness and alcohol/drugs/risks for first-year students.
"The goal is to increase understanding and awareness for first-year students to maximise their wellbeing and ensure they understand how to access all relevant support services available," de la Rey said.
"We have formally requested accommodation provider Campus Living Villages (CLV) to respond to a number of areas of concern," she added in a statement.
"We also anticipate other policy, process and procedural changes being identified in Hon. Kit Toogood QC's findings and recommendations. Our expectation is that any issues will be addressed before commencement in 2020.