"I'm sure he had to suffer. It had to be absolutely horrific in that car for that man."
On the day of LaPointe's death, Russell, 28, was taking him to a doctor's appointment but had taken two packets of the herbal supplement Kratom, the sheriff's office said.
Russell was driving the man to the care home where LaPointe lived but he felt "nauseous" and couldn't finish the journey.
The carer told police he woke "two or three hours later" and was "covered in sweat".
He saw LaPointe in the back of the van and began to do CPR.
After his failure to revive LaPointe, he called his mother and then rang the police.
Russell fled the scene before police arrived and was found in the woods threatening to kill himself, the Sun reports.
Police arrested Russell and were unsure how he had survived the boiling van where LaPointe had died.
A Facebook tribute to LaPointe said: "John has an infectious smile, angelic sweet gentle spirit and so enjoyed watching Barney cartoons on his tablet.
"John was a beautiful human being loved by all and will forever be in our hearts."