Carreyrou said, "They basically waged a scorched earth campaign against me and my sources." Holmes ignored repeated requests from Carreyrou to be interviewed.
VIDEO: Wall Street Journal reporter who broke Theranos fraud story walks through investigation
He does not believe fraud was Holmes' original intent, but that it slowly evolved into that. He says Holmes "dropped out of Stanford truly wanting to follow in the footsteps of great entrepreneurs... "
Holmes would have been the first female tech founder worth a billion dollars.
Theranos briefly went live in Walgreens stores in Arizona and Northern California. Until the Wall Street Journal's reporting, the original intent was to expand to the more than 8,000 Walgreens nationwide.
Eventually as Carreyrou told us, it all fell apart after his story -- which later turned into a book.
RELATED: Theranos founder Elizabeth Holmes indicted on wire fraud charges
"It got the point that the gap between her promises and the reality got so enormous that it became a massive fraud."
In his reporting, Carreyrou says he talked with multiple patients that used Theranos' blood-prick technology but is not sure if anyone lost their lives because of it.
Carreyrou has these words of caution for anyone thinking about a medical startup in Silicon Valley: "The main lesson of the Theranos scandal is this fake it till you make it ethos that has been embedded in the way of doing business in the valley for 30 or 40 years is not applicable to medicine or medical products."