When accused of a crime, most people will naturally wish to express their innocence and explain exactly how they have done nothing wrong. It is only human nature to want to defend oneself against accusations. However, doing so can be disastrous from a legal perspective, which is why it is best to remain silent and seek an attorney at once.
As a police officer or other official accuses a person of a crime, that person is generally under a great deal of stress. That stress will often make even the most intelligent and articulate person misspeak, thereby giving incorrect or otherwise harmful answers to the questions. Moreover, police officers are trained to ask questions in a manner that will produce useful evidence for the prosecution. Furthermore, human memory is imperfect, and the police and prosecution will try to use the smallest inconsistencies against the accused.
Looking back at the hundreds of cases in which I have represented clients who spoke to the police before consulting with me, the majority of those clients caused some amount of harm to their case. Often the harm was small, and did not cause any real problems. Other times, the harm was great. For that reason, I always prefer to hear that a client has chosen to remain silent.
The reality is that many people speak to the police before consulting with an attorney. That is simply a fact of life. As such, a large portion of my work in many criminal cases is seeking to undo the harm that a client has caused by speaking to the police. That can be accomplished through a variety of means, with a Motion to Suppress being the most common approach. If the Motion to Suppress is granted by the court, then the statements made by the client can no longer be used against the client. It is not uncommon for a Motion to Suppress being the single most important aspect of a case, which is why it is so important to handle that Motion correctly.