Investigation is often a very important part of preparing a defense in a criminal case. A skilled investigator can obtain information that could result in winning a trial or obtaining a more favorable plea bargain. Police officers are usually very overloaded with cases and can miss important information or witnesses. Having an investigator that is working for you can bring this information to light that might not have otherwise been discovered.
Most lawyers have several investigators that they work with depending of the type of case.Some investigators are better in a murder investigation and others might be better in a sexual assault or drug case. Picking the right investigator can also be an important factor.
An expert witness can also be invaluable in certain types of cases, especially in cases in which the prosecution has its own experts. A jury will evaluate the witnesses and the weight to be given their testimony. If there are experts on one side but not on the other it can be the difference in the outcome of the trial. Consider the complexity of the case and whether an expert will bolster your defense.
At your initial meeting with your lawyer, you should discuss the need for an investigator to interview witnesses and possible uses for expert witnesses. It should be clear in the fee contract whether the costs of an investigator and expert are part of the fee to be paid by your lawyer or whether such costs will be additional.