The man, "Mr A", returned, with his father, in the morning.
"During the assessment Dr C had difficulty engaging with Mr A," the commissioner said.
"At the completion of his assessment, Dr C concluded that Mr A was experiencing a major depressive disorder, with no imminent risk of self-harm."
He discharged the man and suggested he follow up with his GP for the testicle pain, and for consideration of counselling in the community.
"Mr A returned home with his father. Mr A's parents remained very concerned about Mr A.
"Mr A subsequently left the house and was later involved in an incident that resulted in injuries causing his death."
The Coroner considered that the evidence was not sufficient to establish that Mr A had attempted to take his own life. In conclusion, the Coroner stated: "[T]he verdict will be left open and the cause of death is as a result of the injuries received in the [incident].
"Dr C commented that in his view any discussion regarding the correctness of his risk assessments and the use of the Mental Health Act are dependent on the cause of Mr A's death.
"Dr C stated that given that there is uncertainty regarding how Mr A died ... any reasoning based on an assumption of suicide is speculative.
"Dr C advised that since this incident, when dealing with a patient in distress where the level of engagement is limited, he is now 'particularly' aware of gathering information from other sources and obtaining independent opinion from family before deciding on a treatment plan."
The commissioner found the psychiatrist breached the code of patients' rights by not providing services with reasonable care and skill.
His failings included not ascertaining the parents' views on the man's level of risk and not adequately assessing his level of risk at the second assessment.
He also failed in not admitting the man to a mental health unit; in not offering ongoing specialist follow-up; and in not giving guidelines to the man's GP.
The psychiatrist was told to write an apology to the family and to do more training on communication with patients and further develop his risk assessment skills.
The Medical Council is assessing his performance.
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906 (Palmerston North and Levin)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Samaritans: 0800 726 666 (available 24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.