The coroner's report said 16-year-old Joseph Loudon died from choking on his own vomit, caused by having alcohol and the drug papaverine in his system. Papaverine is a drug that can be used to treat impotence.
Loudon's family has always questioned how papaverine could have ended up in his system.
On Monday, family members say they got their answer.
Staff with the organ donation program injected him with it right after his death, before his organs were harvested.
The family has received a letter from the organ transplant bank explaining what happened.
Loudon's death sparked renewed promises in Orinda to crack down on underage drinking.
However, this new school year is already off to a rough start.
Orinda police say they busted up a party over the weekend full of teenagers and alcohol.
Seven were cited, including one girl who crashed her car into another car, then slammed into a utility pole. Thankfully, no one was hurt.