Methamphetamine was found in the offending vehicle that killed three people in a crash last month.
Police have told Stuff that methamphetamine, consistent with personal use, was found in the ute driven by Haydn David Clark, 20, who crashed killing himself and a married couple near Thames on April 19.
The Drury man crossed the centre line and collided with a car in which Jocelyn Anne Fielder, 64, and her husband Ian, 66, were travelling, near the Kopu Bridge on State Highway 25.
Clark's father Jim, 54, was critically injured but has since been discharged.
Police said the ute driven by Clark had been reported stolen after an Auckland purchase believed to have gone wrong.
Clark was also on bail for drugs charges, including manufacturing and supply of methamphetamine, and had absconded from his bail address. He was in breach of his 24-hour curfew at the time.
He also had a history of speeding and crashes, and was also on active driving charges including while disqualified third and subsequent, failing to stop for police and dangerous driving.
He was prohibited from driving and banned from associating with his father.
Eastern Waikato Police investigations manager, Detective Senior Sergeant Stephen Ambler told Stuff that initial indications suggested Clark caused the crash but investigations were ongoing.
"This is a really serious crash where three people have died. We need to do our very best to make sure both victim's families knows why and how this happened."