Why has David Laws not been prosecuted for apparently committing the same crime as Jim Devine jailed today?

Jim Devine ex-MP has today been jailed for fiddling his parliamentary expenses. I have no argument with this he got what he deserved for betraying public trust however what I don't understand is why no prosecution has been brought against David Laws MP who it appears illegally and knowingly claimed around �40,000 in rent paid to his partner. Could it be that Laws is a "golden boy" who Cameron and Clegg want to get back into their government? Devine fiddled something like �9,000 I believe substantially less than the amount Laws appears to have falsely claimed and although Laws has paid some of the money back that does not absolve him in law from being prosecuted if he has in fact committed a crime. Laws is a multi-millionaire by the way.