A good criminal lawyer will not support defendants who commit perjury. One of the primary obligations of this professional is candor to the representatives of a court. If it appears that a client is guilty, a criminal lawyer should tell it to the judge and rest of the jury.
Once the particular expert is picked out of the pool of available options, he or she should zealously represent the client. Collecting information, visiting the crime scenes, get familiar with the relevant laws, interviewing witnesses – all of those are integral steps of preparing a viable defense.