Their loved one, John D. Grubs Jr., was lying in a hospital tended by the family of the boy who actually died, John's friend Jeremy Hylemon.
The mix-up wasn't discovered for three days, until Saturday's funeral.
"People have been asking me how this happened, and I have to tell them, 'I don't know,'" said Richard Siclari, a Jefferson County deputy coroner.
Many officials and hospital employees blamed grief for the bad identifications by both families. But Jeremy's relatives say they raised questions but were brushed off.
Jeremy, 15, and John, 16, were together July 31 when their car left the road and hit a tree. Both were flown to Louisville for treatment, and the families were called in. Jeremy died later that morning at University Hospital; John had critical injuries but survived.
At Saturday's funeral, John's friend Joe Gatrost noticed that the corpse had pierced ears. "The only reason I had doubts was because John didn't have his ears pierced," Gatrost said.
Jeremy's maternal grandmother, Carol Kerns, was called to the service and realized the boy in the coffin was not John but her grandson, said Meade County Sheriff's Deputy William Sego. Otherwise, the body would have been cremated, Sego said.
The Jefferson County coroner's office confirmed the identification Monday with dental records.
Kerns said that her daughter — Hylemon's mother, Kim — questioned whether the injured boy was Jeremy, but hospital workers dismissed her.
"She said, 'That don't look like Jeremy. His nose is too big.' The hospital said he suffered head trauma when he went through the windshield. She said, 'Well, his upper lip is fatter.' And they said that's due to the head trauma," Kerns told The Courier-Journal of Louisville.
"Every time she'd say something, they'd say it was head trauma," Kerns said.
Hospital spokeswoman Shelly Hazle denied the family account, saying relatives did identify the injured teen as Hylemon.
Siclari had escorted John's family to a hospital room to see the dead boy. The body didn't have any facial injuries, but a cloth covered the top of the head because of a severe head injury.
"They cried and prayed and said, 'This is John,'" Siclari said. "It's just a terrible case of mistaken identity."
Jeremy's family, meanwhile, watched over the boy who turned out to be John for three days at the same hospital.
The hospital has since declined to say whether John is still at the hospital or release his condition.