A leading Papua New Guinea anti-corruption officer has dismissed suggestions that the prime minister should not be questioned in relation to a fraud case until the "main suspect" is convicted.
The police fraud squad has been probing the prime minister Peter O'Neill's role in allegedly illegal state payments to a law firm, Paraka Lawyers.
The squad has sought to arrest Mr O'Neill since 2014 however this has been frustrated by numerous legal challenges.
The head of the anti-corruption investigative unit Taskforce Sweep, Sam Koim, said the firm's principal, Paul Paraka, is facing many criminal charges but has managed to stave off conviction by filing a series of legal challenges.
Mr Koim said this doesn't mean Peter O'Neill should not also face the courts.
"But that argument does not have sound legal basis. Paraka and other co-conspirators have to be prosecuted together," Mr Koim said. "Lawyers in Papua New Guinea have become, if you like, ingenious in devising all manner of applications and putting roadblocks after roadbloacks in between the process, and they are frustrating it."
However, a Supreme Court decision on Thursday has peeled back one of the layers of legal obfuscation around the case being probed by the fraud squad.
Mr O'Neill's lawyers had filed a "slip rule" application arguing that judges made an error in dismissing an appeal by him and finance minister James Marape, lifting orders preventing them from being arrested in relation to the case.
The Supreme Court however has dismissed this slip application.
A separate court order still prevents police from arresting Mr O'Neill, but not Mr Marape.