As a general rule, the attorney foots all the bills incurred as a result of research and other important work in obtaining proof and hiring professional witnesses. Those costs are generally charged to the client after the case is won. The fee is above and beyond the percentage the attorney charges for the case if it is won.
There are a few things to be aware of in these cases. Some attorneys will attempt to charge the client upfront for the fees he or she will incur during the process of collecting important information. Do not agree to this because it can easily run above $100,000 by the end of the trial date. Some lawyers will also require that the client repay these fees regardless of whether the case is won or not. That is not a generally accepted practice, though it is certainly legal. It is highly recommended that you walk away from any lawyer that asks for this requirement. Do not sign any paperwork to this effect. Be certain to read all contracts that the lawyer asks you to sign to ensure that you do not fall into this trap. Most lawyers commonly accept these fees as a loss if they do not win the case.