I assume boro1986 is being flippant.
The fraud dept. can decide to prosecute or they can propose a different solution, such as acceptance of the fraud with a liability to repay, possibly with a penalty added. If the person does not accept this then I think they either have to prosecute or drop it. What they will do depends on their view of the strength of their case. Even if they drop it as a fraud case they can still terminate the benefit concerned if they consider the conditions for it are no longer met.
I don't know whether they can suspend incapacity benefit, but they can end it - as above. It would then be neccesary to claim job seekers allowance or income support or put in a new application for incapacity benefit.
If you are in this position it could be worthwhile getting advice from your local CAB or other welfare rights advice service.