I cannot overemphasize the value of having a seasoned private investigator on a case for the overall chances of success of defending a criminal case. Oftentimes, criminal cases involve eyewitnesses and circumstantial evidence. Many times, the police overlook other possible witnesses to the crime or fail to thoroughly interview the witnesses of the crime. I private investigator is trained to find the missing witnesses and to get additional information out of the witnesses that were previously interviewed. Oftentimes, the police summarize what an eyewitness says but fail to get a written statement from the person. Those summaries are often inaccurate or false in worse case scenarios. A PI can sit-down with the person and get a complete and accurate description of what really happened, which can lead to testimony that can acquit the client at trial.
Just as a private investigator is important to a solid defense, so is a polygrapher. When a client insists that they are innocent and haven't committed the crime they've been accused of, I will often bring in a well-respected polygrapher to confirm the client's story. If the client is lying, no one but me, the polygrapher and the client will ever know. If the client is being truthful and is really innocent of the charge, we can bring that evidence to the attention of the DA and share that information with him or her. Oftentimes, this will result in a dismissal of the charges or the DA will ask the client to submit to a polygraph done by the police, which if he/she passes, will result in a dismissal of the charges. In most cases, if the client insists that they are innocent, conducting a polygraph examination is a no-brainer.
There is more to defending criminal cases than just fancy talk and reviewing a couple of police reports. A good defense attorney will have a trusted team of professionals such as a PI and polygrapher that he is comfortable working with and who have reputations for high levels of professionalism and integrity. Winning a case before it ever goes to trial or even during trial is often a team based accomplishment in the criminal defense field. If your criminal defense attorney doesn't have access to these people and other skilled professionals / experts, you might want to look for a different defense attorney.