There are claims Mr Horan improperly accessed his dying mother's bank account, which are being investigated.
Mr Horan admits using his parliamentary mobile phone 144 times while an MP to place bets with the TAB, at a total cost to the taxpayer of about $20. This was one of the reasons New Zealand First expelled him.
Mr Horan says he does not have a gambling problem and has never stolen money from his mother. However, he does not deny receiving money from her.
Yes, everyone is innocent until proven guilty, but in cases like these where allegations continue to swirl around an MP, the politician needs to put the matter to rest swiftly or stand down until it is sorted.
But Mr Horan has done neither and is not challenging his expulsion, instead choosing to become an independent MP.
Putting the crux of the Horan case to one side, this matter raises an important issue when it comes to list MPs.
List MPs, like Mr Horan was, are not elected by the people to represent them in their electorate. They sail into the corridors of power based on their party vote.
There has been much hand-wringing over this since the Horan issue became public. MPs are frustrated but Prime Minister John Key says finding a solution is not easy.
There used to be a law that MPs couldn't defect from one party to another but it expired in 2005. Attempts to revive it have failed and there are concerns it could be used by a party leader to get rid of rivals or members they don't get on with.
Why does this have to be so hard? Surely a law could be drafted that protects both taxpayers and the MP, ensuring a fair process and using the courts as a last resort.
Independent MPs struggle to be effective. At a time when there is huge financial pressure on the country, when businesses are struggling and people are losing their jobs, I do not believe taxpayers should have to pay Mr Horan.
Voters will have the final say on this but that's two years - and many thousands of dollars - away. Based on everything I have seen and read, I believe Mr Horan does not have the mandate to stay in Parliament.