"But when this guy, using an alias, started writing on Facebook the address of our houses in San Francisco and New Zealand, together with photos, and going on to make terrible comments about my family, it had gone too far.
"It was abusive and menacing. This was not freedom of speech - it was a really nasty vendetta aimed at my family and me."
Spithill enlisted the help of a trusted Kiwi friend, whose father and brother were private investigators.
"They didn't muck around. Within a few hours, they were able to pinpoint the perpetrator - he was a Kiwi living in London," reports Stuff.
"However, instead of sending the police to his front door, the investigators contacted a rather tall, somewhat imposing Bulgarian gentleman they knew, who subsequently paid him a visit.
"Within an hour, we had a photo of the offender, a signed statement from him and a guarantee that everything he had written would be removed immediately.
"I was surprised and impressed how easy it was for experts to track down this lowlife."
Spithill admitted he had purposely pushed the envelope with his mind games, as his team found themselves in their desperate position.
"Of course I had been a bit cocky and arrogant at the press conferences during the Cup match, but that was part of the game. I wanted to unsettle the Kiwis, especially since I believed they might be vulnerable."
When team-mate Joey Newton approached Spithill after one of the press conferences, telling his skipper the Kiwis weren't enjoying his comments in there, Spithill said that only encouraged him to "keep it going and even turn up the heat a notch".