There has been considerable speculation swirling around Marshall's future after it emerged earlier this year he was disillusioned with the club for refusing to honour a handshake agreement over an upgraded contract.
The 28-year-old has another two years left on his contract with the club he an NRL premiership with in 2005 but has a clause that allows an upgrade following an increase in the salary cap due to a new broadcasting deal.
He has said he wouldn't contemplate playing for another NRL outfit, raising speculation he might switch to rugby union and could also chase inclusion in the New Zealand sevens side for the 2016 Rio Olympics.
Sir John Kirwan admitted recently he had been in touch with Marshall's agent Martin Tauber about joining the Blues but there has also been interest from the Waratahs as well as rugby clubs in Japan.
While Marshall would be a crowd-puller in Auckland, he would likely have to take a significant pay cut to play for the Blues and Japan can offer more lucrative deals. The Blues are also interested in luring promising All Blacks first five-eighths Beauden Barrett from the Hurricanes.
"Benji will play out the balance of the 2013 year but will seek an early release." Tauber told the Sydney Morning Herald.
"This has been a very difficult decision. This young man has given 12 years of his football life to a club that he has great regard and affection for," Tauber said."However with what's transpired, he believes it's time for him to take up another challenge, for what will basically be the next five years of his life."
Marshall's decision will also be closely followed by Stephen Kearney as the Kiwis coach plots the defence of the World Cup in the UK and France later this year.
Kearney replaced Marshall as captain ahead of this year's Anzac test in favour of Warriors skipper Simon Mannering but Marshall was still expected to be an important member of the final squad.
- Michael Brown of APNZ
