A loved one who didn't want to be named said she had been told Lindsay's death was a suspected suicide.
She had known him for many years and was "wrecked" at the news of his death.
"I'm struggling to come to terms with how it happened. Are they not aware of young men that are suicidal or, you know, depressed?
"The questions to be answered are how it happened and why did it happen, and where were the guards, where was the secure environment?"
She described herself as "appalled", as well as "angry and upset" over his death.
She said Lindsay had fallen in with a bad crowd, finding "family" in the Nomads gang, but that she was told he had given up his patch and was trying to leave the gang before his death. She did not know what he was in prison for at the time.
"He was a bad boy but a loving bad boy.
"To me he was like a son ... I always had a special place for him."
She described a man who was hard-working, loved animals, and would "do anything for anyone".
"He would give you the shirt off his back."
When asked about how the death was able to happen, a Corrections spokeswoman would not comment.
"As the death remains subject to investigation, and the Coroner is yet to determine the cause, we are not able to provide any further information," she said.
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
• 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)
• Rainbow Youth: (09) 376 4155
• Helpline: 1737
If it is an emergency and you feel like you or someone else is at risk, call 111.