She can persist in an investigation even when the client who originated it asks her to stop or is dead, and sometimes she starts an investigation on her own without a client at all. Sometimes at the end of such a case somebody who benefited from her efforts - not necessarily the original client - volunteers to pay her.
She can continue investigating even when the person who hired her stops or dies, and occasionally she starts investigations independently without a client.  Sometimes, those who benefit from her work, not necessarily the initial client, offer payment at the end of the case.