As a former prosecutor of thirteen years, I can tell you that under no circumstances should a person speak with law enforcement BEFORE speaking with a qualified criminal defense attorney. This holds true even if you have not yet been arrested, but are merely under investigation for a criminal matter.
The primary reason is that anything you say to law enforcement can and will be used against you in a court of law should you make any incriminating statements. However, an attorney acting on your behalf can answer any questions law enforcement has and those answers can not be used against you. Another reason you should never speak with law enforcement (pre-arrest or post-arrest) is that police are legally permitted to lie to you about what evidence they have and what witnesses they may have whom are prepared to testify against you. It is very common for a person to unwittingly walk themself into a criminal charge by giving the police information that ultimately leads to their arrest.
Since the police have no duty to be truthful with you (and often are NOT) the only way to level the playing field and protect your rights is to have a seasoned criminal defense attorney in your corner from the outset. At stake is nothing less than your freedom!