He and his wife, Patti Napier, have put 150,000km on their car, worn out two sets of tyres and spent more time "than they would like to think" in prison, visiting David Bain every month for 12 years.
The devoted supporters were yesterday elated at the not-guilty verdict reached by the jury.
"It is fan-bloody-tastic," Mr Robertson said.
He said helping Mr Bain had been "a big chunk of our life".
He said his life would now recover some semblance of normality - after a big celebration.
The couple had celebrated with Mr Bain when he was granted bail in Christchurch in May 2007, following the Privy Council quashing of his convictions.
Mr Robertson said Mr Bain's supporters, who he estimated filled 80% of the public gallery, were incredibly nervous before the verdict.
He arrived in Christchurch this week and said the tension was palpable.
Mr Robertson said he did not know whether Mr Bain would come back to Dunedin to see his supporters and visit the city in which he grew up.
As a condition of his bail, Mr Bain had not been allowed to visit the South Island, where many of his extended family live.
"I don't think he has given any thought to what happens now. "He has a got a lot of friends in Dunedin who would just love him to come stay with them."
Friends of David Bain group head Catherine Spencer, who was also in Christchurch for the outcome of the trial, said the verdict was "fantastic news" which had taken too long to come.
Ms Spencer said there would be big parties with Mr Bain and all his supporters.
Emotion was running high among supporters in Christchurch yesterday, she said.
"This news has taken far too long, but I knew it would happen one day."
