It has never been disclosed how much of the $300,000 reward was paid or to whom, but it is believed all of it was paid out and some of that went to the thieves.
Mr Bensemann said he would discuss extending the second reward's deadline with Police Commissioner Howard Broad and Lord Ashcroft in the next week, but the sum offered would not change.
A spokesman for Mr Broad said it was too early to say whether he would be amenable to the idea.
The medals were stolen in a night-time heist at the Army Museum and although police have yet to publicly identify the suspects, they say they are confident they are "working on the right people".
Among the medals stolen were nine Victoria Crosses, including the double VC awarded to Captain Charles Upham.
Two men, who because of court orders can only be called K and W, have been identified in media reports as suspects.
W was freed on bail three days before the medals were stolen after brokering a deal with police over the return of a Goldie painting taken from Auckland University.
Mr Bensemann would not comment on whether K and W were the same people police were focusing on; nor would he reveal any new information about the case.
He only said it was no surprise the second reward had not been claimed, as officers were up against "a very tight group" who knew about the theft.
Lawyer Chris Comeskey, who brokered the return of the medals and was later revealed to have been involved in W's Goldie deal, said the $200,000 had not had the "desired effect" and the police investigation was now "historical".
"I suspect it's been de-energised by the fact the medals have been returned."
But Mr Bensemann said there had been no scaling back of resources, and six police staff in Palmerston North, Taumarunui and Auckland continued to work full-time on solving the case.
"We haven't taken our foot off the pedal," he said.
The medals have yet to be returned to the Waiouru museum, but the Army has promised they will go back on public display.
Mr Bensemann said a forensic examination of the medals was likely to be completed in three to four weeks, and planning for a handover would begin after that.
Museum director Colonel Raymond Seymour said he was happy for police to take as long as they needed to examine the medals if it helped to catch the thieves.