OTTAWA -- The NDP is asking Canada's director of public prosecutions to look at the evidence collected by the RCMP in the Mike Duffy case to determine if charges should be laid against other people as well.

The Mounties have filed 31 charges against Duffy related to his housing and travel expense claims, accusing him of misspending more than $200,000.

But Charlie Angus, the NDP ethics critic, is wondering why others haven't been charged.

Nigel Wright, former chief of staff to Prime Minister Stephen Harper, gave Duffy $90,000 to repay his questioned expense claims. Police have already said Wright won't face charges.

Angus says he doesn't question the RCMP investigation, but says the independent director of public prosecutions should have been involved.

He says a review of the evidence might settle some questions that have swirled around the Duffy scandal.